A noun class system is a grammatical system that some languages use to overtly categorize nouns. Noun classes are
- often based, at least in part, on characteristics (such as gender, animacy, shape) of the referents of some of the nouns in each class, and
- distinguished by
- an affix on the noun or by a clitic or word in the noun phrase, and
- agreement affixes on noun phrase constituents and on the verb.
A finer distinction may be made, according to R. M. W. Dixon, between prototypical noun classes (a grammatical system) and noun classifiers (a lexical set).
Noun class systems have the following characteristics:
- They typically comprise a closed set of two to twenty classes, into which all nouns in the language are divided.
- Typically, few or no nouns can occur in more than one class.
- Expression of the noun class is obligatory in all contexts.
- Class may be marked on the noun itself, but will also always be marked on other constituents in the noun phrase or in the sentence that show concord (agreement) with the noun.
Examples: Most types of gender systems and concord systems; many IndoEuropean languages, Bantu languages, Niger Congo languages, Dyirbal (Australian)
Conversely, languages with noun classifier sets have the following characteristics:
- They typically involve 20 or more classifiers (separate lexemes that co-occur with the noun). One hundred classifiers are common, and 400 are attested. Not every noun must take a classifier.
- Many nouns can occur with more than one classifier.
- The classifier occurs in only some syntactic environments. In addition, use of the classifier may be influenced by the pragmatics of style and the choice of written or spoken mode. (Often, the more formal the style, the richer the variety of classifiers used, and the higher the frequency of their use.)
- Noun classifiers are always free lexical items that occur in the same noun phrase as the noun they qualify. They never form a morphological unit with the noun, and there is never agreement marking on the verb.
Note: Noun classifiers are usually derived from words used as names of concrete, discrete, moveable objects.
Examples: Japanese, Chinese, Southeast Asian languages, Austronesian languages, Mayan languages, American Sign Language
Not all noun classifying languages fit neatly into one of these two prototypes of linguistic categorization. Various intermediate types are attested in languages of the Americas.
In Spanish, nouns are classified by gender. In the following words, the suffixes -a ‘FEMININE’ and -o ‘MASCULINE’ express the noun class on the noun, and the articles la ‘FEMININE’ and el ‘MASCULINE’ agree with the nouns accordingly:
- la hija ‘the daughter’
- el hijo ‘the son’
- la mesa ‘the table’
- el mercado ‘the market’