Copula (linguistics)

In linguistics, a copula (plural: copulae or copulas) is a word used to link the subject of a sentence with a predicate (a subject complement). The word copula derives from the Latin noun for a link or tie that connects two different things.

A copula is often a verb or a verb-like word, though this is not universally the case. A verb that is a copula is sometimes called a copulative or copular verb. In English primary education grammar courses, a copula is often called a linking verb. Other copulae show more resemblances to pronouns. This is the case for Classical Chinese and Guarani, for instance. In highly synthetic languages, copulae are often suffixes, attached to a noun, that may still behave otherwise like ordinary verbs, for example -u- in Eskimo languages. In some other languages, such as Beja and Ket, the copula takes the form of suffixes that attach to a noun but are distinct from the person agreement markers used on predicative verbs. This phenomenon is known as nonverbal person agreement or nonverbal subject agreement and the relevant markers are always established as deriving from cliticised independent pronouns.

In general, the term copula is used to refer to the main copular verb(s) in a language. In the case of English, this is the verb to be. The term can also be used to refer to some other verbs in the language that fulfill similar functions. Other English copulae include to become, to get, to feel, and to seem. Other verbs can have secondary uses as copulative verbs. In the following example, the past tense of the verb to fall is used as a copula: "The zebra fell victim to the lion." These extra copulae are sometimes called "semi-copulae" or "pseudo-copulae".

Most languages have one main copula, but some languages, like Spanish and Thai, have more than one, and some have none.

English
Copulae have multiple uses.

Use
Several uses of the copula can be categorized:
 * Identity: "I only want to be myself." "When the area behind the dam fills, it will be a lake." "The Morning Star is the Evening Star." "Boys will be boys."
 * Class membership. To belong to a set or class: "She could be married." "Dogs are canines." "Moscow is a large city." Depending on one's point of view, all other uses can be considered derivatives of this use, including the following non-copular uses in English, as they all express a subset relationship.


 * Predication (property and relation attribution): "It hurts to be blue." "Will that house be big enough?" "The hen is next to the cockerel." "I am confused." Such attributes may also relate to temporary conditions as well as inherent qualities: "I will be tired after running." "Will you be going to the play tomorrow?" but please note that a linking verb has nothing to do with these so called "Be"- verbs.(see below)

Non-copular uses
The auxiliary verb function derives from the copular function; and, depending on one's point of view, one can still interpret the verb as a copula and the following verbal form as being adjectival. Abelard in his Dialectica made an argument against the idea that the copula can express existence based on a reductio ad absurdum.
 * The verb that often is used as a copula can also be used as an auxiliary verb:
 * To form the passive voice: "I was told that you wanted to see me"
 * To form progressive tenses in English: "It is raining"
 * "To be" also has a non-copular use meaning "to exist" (existential verb): "I want only to be, and that is enough." "There's no sense in making a scientific inquiry about what species the Loch Ness Monster is, without first establishing that the Loch Ness Monster indeed is." "To be or not to be, that is the question." "I think therefore I am."

Copula omission
In informal speech of English, the copula may be dropped. This is a feature of African American Vernacular English but is also used by a variety of English speakers in informal contexts. An example: "Where you at? We at the store."

Double copula
The double copula is the use of two successive copulae when only one is necessary, as in My point is, is that.... Use of the double copula is one of the disputes in English grammar.

Conjugation
As in most Indo-European languages, the English copula is the most irregular verb because of constant use. Most English verbs (traditionally known as "weak verbs") have just four separate forms, e.g., "start", "starts", "starting", "started". A sizable minority (traditionally known as "strong verbs") have five separate forms, e.g., "begin", "begins", "beginning", "began", "begun". "To be" is a very special case in having eight forms: "be", "am", "is", "are", "being", "was", "were", "been". At one time, it had even more, including "art", "wast", "wert", and, on occasion, "beest" as a subjunctive.

Subset relator
From one perspective, the copula always relates two things as subsets. Take the following examples:
 * 1) John is a doctor.
 * 2) John and Mary are doctors.
 * 3) Doctors are educated.
 * 4) Mary is running.
 * 5) Running is fun.

Example 1 includes John in the set of all doctors. Example 2 includes John and Mary both in the set of all doctors. Example 3 includes the set of doctors in the set of those who are educated.

Example 4 is different. Example 4 includes Mary's state at the time of utterance in the set of states consistent with running. Example 5 then includes the set of states consistent with running in the set of states consistent with fun.

Distinguishing between a copula and an action verb
A copula and an action verb can generally be differentiated by trying to substitute the verb with a form of "to seem" or "to be".


 * Example of an Action Verb: Sam looks at lettuce. Sam seems at lettuce? Sam is at lettuce? The latter two don't make sense, so "looks" in this case is being used as an action verb.


 * Example of a Copula: Sam looks happy. Sam seems happy? Sam is happy? The latter two make sense; "looks" is used as a copula in this case.

Note that this approach falters, in part, with the verb "to appear". In the sentence "Sam appears to be happy", "appears" is a copula. Yet, "seems" but not "is" can be substituted: "Sam is to be happy" means something else entirely.

Copulae in other languages
In Indo-European languages, the words meaning "to be" often sound similar to each other. Due to the high frequency of their use, their inflection retains a considerable degree of similarity in some cases. Thus, for example, the English form is is an apparent cognate of German ist, Latin est and Russian  jest' , even though the Germanic, Italic, and Slavic language groups split at least three thousand years ago. The origins of the Indo-European copulae can be traced back to four different stems *es- (*h1es-), *sta- (*steh2-), *wes- and *bhu- (*bʰuH-) in most Indo-European languages.

Georgian and English
As in English, the verb "to be" (qopna) is irregular in Georgian (a Kartvelian language); different verb roots are employed in different tenses. The roots -ar-, -kn-, -qav-, and -qop- (past participle) are used in the present tense, future tense, past tense and the perfective tenses respectively. Examples:


 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * Masc'avlebeli var.
 * "I am a teacher."
 * Masc'avlebeli viknebi.
 * "I will be a teacher."
 * Masc'avlebeli viqavi.
 * "I was a teacher."
 * Masc'avlebeli vqopilvar.
 * "I have been a teacher."
 * Masc'avlebeli vqopiliqavi.
 * "I had been a teacher."
 * }
 * "I have been a teacher."
 * Masc'avlebeli vqopiliqavi.
 * "I had been a teacher."
 * }
 * }

Note that, in the last two examples (perfect and pluperfect), two roots are used in one verb compound. In the perfective tense, the root qop (which is the expected root for the perfective tense) is followed by the root ar, which is the root for the present tense. In the pluperfective tense, again, the root qop is followed by the past tense root qav. This formation is very similar to German (an Indo-European language), where the perfective and the pluperfective are expressed in the following way:


 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * Ich bin Lehrer gewesen.
 * "I have been a teacher", literally "I am teacher been."
 * Ich war Lehrer gewesen.
 * "I had been a teacher", literally "I was teacher been."
 * }
 * "I had been a teacher", literally "I was teacher been."
 * }

Here, gewesen is the past participle of sein ("to be") in German. In both examples, as in Georgian, this participle is used together with the present and the past forms of the verb in order to conjugate for the perfect and the pluperfect aspects.

Zero copula (Semitic languages, Quechuan languages, Hungarian, Russian, Ancient Greek)
In some languages, copula omission occurs within a particular grammatical context. For example, speakers of Russian, Hungarian, Hebrew, Arabic, and Quechuan languages consistently drop the copula in present tense: Russian: я &mdash; человек, ya &mdash; chelovek "I (am) a human"; Hungarian: ő ember, "he (is) a human"; Hebrew: אני בן-אדם "I (am a) human", Arabic: أنا إنسان ʔænæː insæːn "I am human"; Southern Quechua: payqa runam "s/he (is) a human". This usage is known generically as the zero copula. Note that in other tenses (sometimes in other persons besides third singular) the copula usually reappears.

In Ancient Greek, when an adjective precedes a noun with an article, the copula is understood. Thus, ὁ οἴκος ἐστὶ μακρός, "the house is large," can be written μακρός ὁ οἴκος, "large the house (is)."

In Quechua —Southern Quechua used for the examples—, zero copula is restricted to present tense in third person singular only (kan): Payqa runam &mdash; "(s)he is a human"; but: (paykuna) runakunam kanku "(they) are human".

In Hungarian, zero copula is restricted to present tense in third person singular and plural: Ő ember/Ők emberek &mdash; "s/he is a human"/"they are humans"; but: (én) ember vagyok "I am a human", (te) ember vagy "you are a human", mi emberek vagyunk "we are humans", (ti) emberek vagytok "you (all) are humans". The copula also reappears for stating locations: az emberek a házban vannak, "the people are in the house," and for stating time: hat óra van, "it is six o'clock." However, the copula may optionally get omitted in colloquial language: hat óra (van), "it is six o'clock."

Hungarian uses a copula to say Itt van Róbert "Bob is here" (and this not only with regard to third person singular/plural), but not to say Róbert öreg "Bob is old". This is to relate a subject to a more temporary condition/state taking place in space (very often in the sense of Lojban zvati: la rabyrt. zvati ne'i le zdani "Robert is in the house").

Further restrictions may apply before omission is permitted. For example, in the Irish language, is, the present tense of the copula, may be omitted when the predicate is a noun. Ba the past/conditional cannot be deleted. If the present copula is omitted, the following pronoun é, í, iad preceding the noun is omitted as well.

Essence versus state
Romance copulae usually consist of two different verbs that can be translated as "to be", the main one from the Latin esse (derived from *es-), and a secondary one from stare (derived from *sta-). This is found in Spanish, Catalan, Portuguese, and to a lesser extent Italian, but not in French or Romanian. The difference is that the first usually refers to essential characteristics, while the second refers to states and situations, e.g., "Bob is old" versus "Bob is well". A similar division is found in the non-Romance Basque language (viz. egon and izan). (Note that the English words just used, "essential" and "state", are also cognate with the Latin infinitives esse and stare.) In Spanish, the high degree of verbal inflection, plus the existence of two copulae (ser and estar), means that there are 105 separate forms to express the copula, compared to eight in English and one in Chinese.

In some cases, the verb itself changes the meaning of the adjective/sentence. The following examples are from Portuguese:

In certain languages, not only are there two copulae but the syntax is also changed when one is distinguishing between states or situations and essential characteristics. For example, in Irish and Scottish Gaelic, describing the subject's state or situation typically uses the normal VSO ordering with the verb bí. The copula is, which is used to state essential characteristics or equivalences, requires a change in word order so that the subject does not immediately follow the copula (see Irish syntax).

In Slavic languages, a similar distinction is made by putting a state in the instrumental case, while characteristics are in the nominative. This is used with all the copulae (e.g., "become" is normally used with the instrumental). It also allows the distinction to be made when the copula is omitted (zero copula) in East Slavic languages (in other Slavic languages the copula is not omitted).

Irish
In Irish, the copula is used for things that are in a permanent state.


 * {| border="0" cellspacing="2" cellpadding="1" valign="top"


 * align=left valign=top| || align=right valign=top |  || align=left valign=top |
 * Is fear Liam|| "Liam is a man" ||(lit., is man Liam)
 * Is leabhar &eacute; sin|| "That is a book" ||(lit., is book it that)
 * }
 * Is leabhar &eacute; sin|| "That is a book" ||(lit., is book it that)
 * }

The word "is" is the copula (rhymes with the English word "hiss"). The pronoun used with the copula is different from the normal pronoun. For a masculine singular noun, "&eacute;" is used (for "he" or "it"), as opposed to the normal pronoun "s&eacute;"; for a feminine singular noun, "&iacute;" is used (for "she" or "it"), as opposed to normal pronoun "s&iacute;"; for plural nouns, "iad" is used (for "they" or "those"), as opposed to the normal pronoun "siad".

To describe non-permanent states, "to be" is used, e.g., Tá mé ag rith "I am running".

This system resembles the Essence versus state distinction of the Romance copula.

Haitian Creole
Haitian Creole, a French-based creole language, has a reputation as being rather exotic from a linguistic standpoint when compared to French and the other Romance languages; and it lives up to this reputation with its copula system. It has three forms of the copula: se, ye, and the zero copula, no word at all (the position of which will be indicated with Ø, just for purposes of illustration).

Although no textual record exists of Haitian at its earliest stages of development from French, se is derived from French c'est, which is the normal French contraction of ce (that) and the copula est (third-person singular of the present indicative of the verb être, ultimately from Latin sum). As Latin sto became ester in Old French and sum became estre, these two verbs merged into modern être before the colonization of Haiti and therefore sto does not appear in Haitian Creole.

The derivation of ye is less obvious; but we can assume that the French source was il est ("he/it is"), which, in rapidly spoken French, is very commonly pronounced as y est (IPA ).

The use of a zero copula is unknown in French, and it is thought to be an innovation from the early days when Haitian was first developing as a Romance-based pidgin. Latin also sometimes used a zero copula.

Which of se / ye / Ø is used in any given copula clause depends on complex syntactic factors that we can superficially summarize in the following four rules:

1. Use Ø (i.e., no word at all) in declarative sentences where the complement is an adjective phrase, prepositional phrase, or adverb phrase:


 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * Li te Ø an Ayiti.
 * "She was in Haiti." || (she past-tense in Haiti)
 * Liv-la Ø jon.
 * "The book is yellow." || (book-the yellow)
 * Timoun-yo Ø lakay.
 * "The kids are [at] home." || (kids-the home)
 * }
 * Timoun-yo Ø lakay.
 * "The kids are [at] home." || (kids-the home)
 * }

2. Use se when the complement is a noun phrase. But note that, whereas other verbs come after any tense/mood/aspect particles (like pa to mark negation, or te to explicitly mark past tense, or ap to mark progressive aspect), se comes before any such particles:


 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * Chal se ekriven.
 * "Charles is writer."
 * Chal se pa ekriven.
 * "Charles is not writer." cf. with the verb kouri ("run"): Chal pa kouri, not Chal kouri pa.
 * Chal, ki se ekriven, pa vini.
 * "Charles, who is writer, not come."
 * }
 * Chal, ki se ekriven, pa vini.
 * "Charles, who is writer, not come."
 * }

3. Use se where French and English have a dummy "it" subject:


 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * Se mwen!
 * "It's me!" French C'est moi!
 * Se pa fasil.
 * "It's not easy," colloquial French C'est pas facile.
 * }
 * "It's not easy," colloquial French C'est pas facile.
 * }

4. Finally, use the other copula form ye in situations where the sentence's syntax leaves the copula at the end of a phrase:


 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * Kijan ou ye?
 * "How you are?"
 * Pou kimoun liv-la te ye?
 * "Whose book was it?" || (of who book-the past-tense is?)
 * M pa konnen kimoun li ye.
 * "I don't know who he is." || (I not know who he is)
 * Se yon ekriven Chal ye.
 * "Charles is a writer!" || (it's a writer Charles is; cf. French C'est un écrivain qu'il est.)
 * }
 * Se yon ekriven Chal ye.
 * "Charles is a writer!" || (it's a writer Charles is; cf. French C'est un écrivain qu'il est.)
 * }
 * }

The above is, however, only a simplified analysis.

Japanese
Japanese has copulae that would most often be translated as one of the so-called be-verbs of English.

The Japanese copula has many forms. The words da and desu are used to predicate sentences, while na and de are particles used within sentences to modify or connect.

Japanese sentences with copulae most often equate one thing with another, that is, they are of the form "A is B." Examples:


 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * 私は学生だ.
 * Watashi wa gakusei da. || "I'm a student." || (lit., I TOPIC student COPULA )
 * これはペンです.
 * Kore wa pen desu. || "This is a pen." || (lit., this TOPIC pen COPULA-POLITE )
 * }
 * Kore wa pen desu. || "This is a pen." || (lit., this TOPIC pen COPULA-POLITE )
 * }

The difference between da and desu appears simple. For instance desu is more formal and polite than da. Thus, many sentences such as the ones below are almost identical in meaning and differ in the speaker's politeness to the addressee and in nuance of how assured the person is of their statement. However, desu may never come before the end of a sentence, and da is used exclusively to delineate subordinate clauses. In addition, da is always declarative, never interrogative.


 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * あれはホテルだ.
 * Are wa hoteru da. || "That's a hotel." || (lit., that TOPIC hotel COPULA )
 * あれはホテルです.
 * Are wa hoteru desu. || "That is a hotel." || (lit., that TOPIC hotel COPULA-POLITE )
 * }
 * Are wa hoteru desu. || "That is a hotel." || (lit., that TOPIC hotel COPULA-POLITE )
 * }

Japanese sentences may be predicated with copulae or with verbs. However, desu may not always be a predicate. In some cases, its only function is to make a sentence predicated with a stative verb more polite. However, da always functions as a predicate, so it cannot be combined with a stative verb, because sentences need only one predicate. See the examples below.


 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * このビールはおいしい.
 * Kono bīru wa oishii. || "This beer is delicious." || (lit., this beer TOPIC be-tasty)
 * このビールはおいしいです.
 * Kono bīru wa oishii desu. || "This beer is good." || (lit., this beer TOPIC be-tasty POLITE )
 * *このビールはおいしいだ.
 * *Kono bīru wa oishii da. || colspan=2 | This is unacceptable because da may only serve as a predicate.
 * }
 * *このビールはおいしいだ.
 * *Kono bīru wa oishii da. || colspan=2 | This is unacceptable because da may only serve as a predicate.
 * }

There are several theories as to the origin of desu; one is that it is a shortened form of であります de arimasu, which is a polite form of である de aru. In general, both forms are used in only writing and more formal situations. Another form, でございます de gozaimasu, which is the more formal version of de arimasu, in the etymological sense a conjugation of でござる de gozaru and an honorific suffix -ます -masu, is also used in some situations and is very polite. Note that de aru and de gozaru are considered to be compounds of a particle で de, and existential verbs aru and gozaru. です desu may be pronounced っす ssu in colloquial speech. The copula is subject to dialectal variation throughout Japan, resulting in forms such as や ya (in Kansai) and じゃ ja (in Hiroshima).

Japanese also has two verbs corresponding to English "to be": aru and iru. They are not copulae but existential verbs. Aru is used for inanimate objects, including plants, whereas iru is used for animate things like people, animals, and robots, though there are exceptions to this generalization.


 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * 本はテーブルにある.
 * Hon wa tēburu ni aru. || "The book is on a table."
 * キムさんはここにいる.
 * Kimu-san wa koko ni iru. || "Kim is here."
 * }
 * Kimu-san wa koko ni iru. || "Kim is here."
 * }

Japanese people, when learning English, usually drop the auxiliary verbs "be" and "do" due to believing incorrectly that "be" is a semantically empty copula equivalent to "desu" and "da".

Korean
For sentences with predicate nominatives, the copula "이다" (i-da) is added to the predicate nominative (with no space in between).


 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * 바나나는 과일이다.
 * Ba-na-na-neun gwa-il-i-da.. || "Bananas are a fruit."
 * }
 * }

Predicate Adjectives can be handled in at least three ways. In all three ways, the adjective and verb are connected as one word.

1) With the copula "이다":


 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * 바나나는 노란색이다.
 * ba-na-na-neun no-ran-saek-i-da.. || "Bananas are yellow."
 * }
 * }

2) With the verb "하다" (ha-da):
 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * 저는 행복하다.
 * Jeo-neun haeng-bok-ha-da.. || "I am happy."
 * }
 * }

3) With stative verbs:


 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * 저는 예쁘다.
 * Jeo-neun yeh-bbeu-da.. || "I am pretty."
 * }
 * }

Some English descriptions do not use the cupola in Korean. For example, instead of saying "Ice cream is delicious", Koreans commonly say "Ice cream has flavor" (With has-flavor often combined into one word, but sometimes not).


 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * 아이스크림는 맛있다.
 * A-i-seu-keu-rim-neun mat-it-da.. || "Ice cream has-flavor" (Ice cream is delicious)
 * 아이스크림는 맛이 있다.
 * A-i-seu-keu-rim-neun mat-i it-da.. || "Ice cream has flavor" (Ice cream is delicious)
 * }
 * A-i-seu-keu-rim-neun mat-i it-da.. || "Ice cream has flavor" (Ice cream is delicious)
 * }

The opposite, ice cream is gross, uses the Korean word "없다" (eopt-da), meaning "to not have".
 * {| border="0" cellspacing="2" cellpadding="1"


 * align=left | || align=right |  || align=left |
 * 아이스크림는 맛없다.
 * A-i-seu-keu-rim-neun mat-eopt-da.. || "Ice cream [doesn't have]-flavor"
 * 아이스크림는 맛이 없다.
 * A-i-seu-keu-rim-neun mat-i eopt-da.. || "Ice cream [doesn't have] flavor"
 * }
 * A-i-seu-keu-rim-neun mat-i eopt-da.. || "Ice cream [doesn't have] flavor"
 * }

Chinese
N.B. The characters used are simplified ones, and the transcriptions given in italics reflect Standard Chinese pronunciation, using the Pinyin system.

In Chinese languages, both states and qualities are, in general, expressed with stative verbs (SV) with no need for a copula, e.g., in Mandarin, "to be tired" (累 lèi), "to be hungry" (饿 è), "to be located at" (在 zài), "to be stupid" (笨 bèn) and so forth. These verbs are usually preceded by an adverb such as 很 hěn ("very") or 不 bù ("not"). A sentence could also simply use a pronoun and a verb: for example, 我饿. wǒ è. "I am hungry."

Only sentences with a noun as the complement (e.g., "this is my sister") use the verb "to be": 是 shì. This is used frequently: For example, instead of having a verb meaning "to be Chinese", the usual expression is "to be a Chinese person", using 是 shì. Some scholars call this verb form an equative verb (EV), as published in some Yale Chinese textbooks.

The history of the Chinese copula 是 is a controversial subject. Before the Han Dynasty, the character served as a demonstrative pronoun meaning "this" (this usage survives in some idioms and proverbs, as well as in Japanese). Some linguists argue that 是 developed into a copula because it often appeared, as a repetitive subject, after the subject of a sentence (in classical Chinese we can say, for example: "George W. Bush, this president of the United States" meaning "George W. Bush is the president of the United States). Other scholars do not completely accept the explanation, proposing that 是 served as a demonstrative pronoun and a copula at the same time in ancient Chinese. Etymologically, 是 developed from the meaning of "straight"; in modern Chinese, however, it can be combined with the modifier 的 de to mean "yes" or to show agreement. e.g. Question: 你的汽车是不是红色的？ nǐ de qìchē shì bú shì hóngsè de? "Is your car red or not?" Response: 是的. shì de. "Is.", meaning "Yes.", or 不是.  bú shì. "Not is.", meaning "No." A more common way of showing that the person asking the question is correct is by simply saying "right" or "correct", 对 duì, which drops the modifier 的 de; the corresponding negative answer is 不对 bú duì, "Not right."

Cantonese uses 係 (Jyutping: hai6) instead of 是.

Siouan languages
In Siouan languages like Lakota, in principle almost all words — according to their structure — are verbs. So, not very unlike in Lojban (see below), not only (transitive, intransitive and so-called 'stative') verbs but even nouns often behave like verbs and do not need to have copulae.

For example, the word wičháša refers to a man, and the verb "to-be-a-man" is expressed as wimáčhaša/winíčhaša/wičháša (I am/you are/he is a man). Yet there also is a copula héčha (to be a ...) that in most cases is used: wičháša hemáčha/heníčha/héčha (I am/you are/he is a man).

In order to express the statement "I am a doctor of profession," one has to say pezuta wičháša hemáčha. But, in order to express that that person is THE doctor (say, that had been phoned to help), one must use another copula iyé (to be the one): pežúta wičháša (kiŋ) miyé yeló (medicine-man DEF ART I-am-the-one MALE ASSERT).

In order to refer to space (e.g., Robert is in the house), various verbs are used, e.g., yaŋkÁ (lit.: to sit) for humans, or háŋ/hé (to stand upright) for inanimate objects of a certain shape. "Robert is in the house" could be translated as Robert thimáhel yaŋké (yeló), whereas "there's one restaurant next to the gas station" translates as "owótethipi wígli-oínažiŋ kiŋ hél isákhib waŋ hé".

Constructed languages
The constructed language Lojban has copulae, but they are rarely used, and are sometimes viewed with distaste in the Lojban community, because all words that express a predicate can be used as verbs. The three sentences "Bob runs", "Bob is old", and "Bob is a fireman", for instance, would all have the same form in Lojban: ''la bob. bajra, la bob. tolcitno, and la bob. fagdirpre''. There are several different copulae: me turns whatever follows the word me into a verb that means to be what it follows. For example, me la bob. means to be Bob. Another copula is du, which is a verb that means all its arguments are the same thing (equal).

The E-Prime language, based on English, simply avoids the issue by not having a generic copula. It requires instead a specific form such as "remains", "becomes", "lies", or "equals".

Esperanto uses the copula much as English. The infinitive is esti, and the whole conjugation is regular (as with all Esperanto verbs). In addition, adjectival roots can be turned into stative verbs: La ĉielo bluas. "The sky is blue."

Likewise, Ido has a copula that works as English "to be". Its infinitive is esar, and, as is the case in Esperanto, all of its forms are regular: The simple present is esas for all persons; the simple past is esis, the simple future is esos, and the imperative is esez, among a few more forms. However, Ido also has an alternative irregular form for the simple present ("es"), which some Idists frown upon. The possibility to turn adjectives and even nouns into verbs also exist, although this is mostly done by means of an affix, on top of the verbal endings. The affix is "-es-". So, "The sky is blue." can be said as "La cielo bluesas". As can be seen, the suffix "-es-" plus the verbal desinence "-as" are simply the verb "to be" annexed to the adjectival or nominal root.

Interlingua speakers use copulae with the same freedom as speakers of Slavic, Germanic, and Romance languages. In addition to combinations with esser ('to be'), expressions such as cader prede ('to fall prey') are common. Esser is stated, rather than omitted as in Russian.

Existential usage
The existential usage of "to be" is distinct from and yet, in some languages, intimately related to its copulative usage. In language as opposed to formal logic, existence is a predicate rather than a quantifier, and the passage from copulative to existential usage can be subtle. In modern linguistics, one commonly speaks of existential constructions - prototypically involving an expletive like there - rather than existential use of the verb itself. So, for example in English, a sentence like "there is a problem" would be considered an instance of existential construction. Relying on unified theory of copular sentences, it has been proposed that there-sentences are subtypes of inverse copular sentences (see Moro 1997 and "existential sentences and expletive there" in Everaert et al. 2006 for a detailed discussion of this issue and a historical survey of the major proposals).

For example:
 * Arabic: يمكنه أنّ يبدو أنّ يكون ذكياً – Yumkinuhu ʼan yabdu ʼan yakūna ḏakiyyan. &mdash; He can appear (to be) smart.
 * Japanese: 吾輩は猫である. 名前はまだない. Wagahai wa neko de aru. Namae wa mada nai – I am a cat. As yet, I have no name. &mdash; Natsume Sōseki
 * English: To be or not to be, that is the question. &mdash; William Shakespeare
 * English: [Why climb Mount Everest?] Because it is there. &mdash; George Mallory
 * Hebrew: אהיה אשר אהיה Ehyeh asher ehyeh. – I am that I am. &mdash; Exodus 3:14.
 * Russian: Страна, которую ищут дети, есть. – Strana, kotoroju iščut deti,  jest' . – The country, which children are looking for, exists. &mdash; Mikhail Prishvin
 * French: Je pense, donc je suis. – I think; therefore, I am. &mdash; Descartes
 * Latin: Cogito ergo sum. – I think; therefore, I am. &mdash; Descartes
 * Hungarian: Gondolkodom, tehát vagyok. – I think; therefore, I am. &mdash; Descartes
 * Turkish: Düşünüyorum, öyleyse varım. – I think; therefore, I am. &mdash; Descartes
 * Finnish: Ajattelen, siis olen. – I think; therefore, I am. &mdash; Descartes
 * Filipino/Tagalog: Ang kahalagahan ng pagiging seryoso. – The importance of being Earnest. &mdash; Oscar Wilde

Other languages prefer to keep the existential usage entirely separate from the copula. Swedish, for example, reserves vara (to be) for the copula, keeping bli (to become) and finnas (to exist, lit. to be found) for becoming and existing, respectively.
 * Swedish: Vem vill bli miljonär? – Who wants to be a millionaire?. (Literally "Who wants to become millionaire?") &mdash; Bengt Magnusson
 * Swedish: Varför bestiga Mt. Everest? Därför att det finns där. – Why climb Mt. Everest? Because it is there. (Literally "Why climb Mt. Everest? Because it is found there") &mdash; George Mallory

In Spanish, ser (to be) is the copula, and estar (to be, to remain) and existir (to exist) are for being in a place and existing, respectively.
 * Spanish: Pienso, luego existo. – I think; therefore, I am. &mdash; Descartes

In ontology, philosophical discussions of the word "be" and its conjugations takes place over the meaning of the word is, the third person singular form of 'be', and whether the other senses can be reduced to one sense. For example, it is sometimes suggested that the "is" of existence is reducible to the "is" of property attribution or class membership; to be, Aristotle held, is to be something. Of course, the gerund form of "be", being, is its own (vexed) topic: see being and existence.

Unified theory of copular sentences
Along with canonical copular constructions wherein the canonical order of predication is displayed - that is, the subject precedes the predicate - as in "a picture of the wall is the cause of the riot," there can also be a symmetric type wherein the order of the two noun phrases is mirrored as in "the cause of the riot is a picture of the wall" (cf. Everaert et al. 2006). Although these two sentences are superficially very similar, it can be shown that they embody very different properties. So, for example, it is possible to form a sentence like "which riot do you think that a picture of the wall is the cause of" but not "*which wall do you think that the cause of the riot was a picture of". The distinction between these two types of sentences, in the technical sense referred to as "canonical" vs. inverse copular sentences, respectively - and the unified theory of copular sentences associated to it - has been proven to be valid across-languages and has led to some refinement of the theory of clause structure. In particular, it challenges one of the major dogmas of the theory of clause structure, i.e., that the two basic constituents of a sentence Noun Phrase and Verb Phrase are associated to the logical/grammatical functions of subject and predicate (cf. phrase structure rules and sentence (linguistics)).

This perspective has been argued against on empirical grounds, since the Noun Phrase that cooccurs with the Verb Phrase in a copular sentence can be the predicate and the subject be contained in the Verb Phrase. It has been suggested that inverse copular sentences appear to play a sharp role in setting the pro-drop parameter. In Italian, for example, in sentences of the type Noun Phrase verb Noun Phrase, the verb, in general, agrees with the Noun Phrase on the left with one exception: inverse copular sentences. One can construe minimal pairs like the cause of the riot is/*are these pictures of the wall vs. la causa della rivolta sono/*è queste foto del muro: The two sentences are one the gloss of the other with only one difference: The copula is singular in Italian and plural in English. If one does not want to give up the idea that agreement is on the left, then the only option is to assume that pro occurs between the copula and the Noun Phrase on the left. That pro can occur as a predicate must be in fact independently assumed to assign a proper structure to sentences like sono io (am I: "it's me"), which can by no means be considered a transformation of *io sono, which has no meaning.