Grammatical categories

A grammatical category is an analytical class within the grammar of a language, whose members have the same syntactic distribution and recur as structural unit throughout the language, and which share a common property which can be semantic or syntactic.

Each grammatical category has several "exponents", at most one of which marks a constituent of an expression: a noun or noun phrase cannot be marked for singular and plural at the same time, nor can a verb be marked for present and past at the same time.

For example, the category number has the exponents [singular] and [plural] in English and many other languages. In English, the number of a noun such as bird in:


 * The bird is singing.
 * The bird are singing.

is either singular or plural, which is expressed overtly by the absence or presence of the suffix -s. Furthermore, the grammatical number is reflected in agreement between the noun and verb, where the singular number triggers is, and the plural number, are.

Exponents of grammatical categories are often expressed in the same position or 'slot' in the word (such as prefix, suffix or enclitic). An example of this is the Latin cases, which are all suffixal: ''ros, ros, ros, ros, ros. ("rose", in nominative, genitive, dative, accusative, ablative)

Theory
In traditional structural grammar, grammatical categories are semantic distinctions; this is reflected in a morphological or syntactic paradigm. But in generative grammar, which sees meaning as separate from grammar, they are categories that define the distribution of syntactic elements. For structuralists such as Roman Jakobson grammatical categories were lexemes that were based on binary oppositions of "a single feature of meaning that is equally present in all contexts of use". Another way to define a grammatical category is as a category that expresses meanings from a single conceptual domain, contrasts with other such categories, and is expressed through formally similar expressions. Another definition distinguishes grammatical categories from lexical categories, such that the elements in a grammatical category have a common grammatical meaning - that is, they are part of the language's grammatical structure.