In linguistics, the term noun class refers to a system of categorizing nouns. A noun may belong to a given class because of characteristic features of its referent, such as sex, animacy, shape, but counting a given noun among nouns of such or another class is often clearly conventional. Some authors use the term "grammatical gender" as a synonym of "noun class", but others use different definitions for each (see below). Noun classes should not be confused with noun classifiers.
In general, there are three main ways by which natural languages categorize nouns into noun classes:
- according to similarities in their meaning (semantic criterion),
- by grouping them with other nouns that have similar form (morphology), or
- through an arbitrary convention.
Usually, a combination of the three types of criteria is used, though one is more prevalent.
Noun classes form a system of grammatical agreement. The fact that a noun belongs to a given class may imply the presence of:
- agreement affixes on adjectives, pronouns, numerals etc. which are noun phrase constituents,
- agreement affixes on the verb,
- a special form of a pronoun which replaces the noun,
- an affix on the noun,
- a class-specific word in the noun phrase (or in some types of noun phrases).
Modern English expresses noun classes through the third person singular personal pronouns he (male person), she (female person), and it (object, abstraction, or animal), and their other inflected forms. The choice between the relative pronoun who (persons) and which (non-persons) may also be considered a way of categorizing nouns into noun classes. A few nouns also exhibit vestigial noun classes, such as stewardess, where the suffix -ess added to steward denotes a female person. This type of noun affixation is not very frequent in English, but quite common in languages which have the true grammatical gender, including most of the Indo-European family, to which English belongs.
When noun class is expressed on other parts of speech, besides nouns and pronouns, the language is said to have grammatical gender.
In languages without inflectional noun classes, nouns may still be extensively categorized by independent particles called noun classifiers.
Common criteria for noun classes 
Common criteria that define noun classes include:
- animate vs. inanimate (as in Ojibwe)
- rational vs. non-rational (as in Tamil)
- human vs. non-human
- human vs. animal vs. inanimate
- male vs. other
- male human vs. other
- masculine vs. feminine
- masculine vs. feminine vs. neuter
- strong vs. weak
- augmentative vs. diminutive
See Swahili for the semantic motivations for an elaborate noun-class system.
Language families 
Algonquian languages 
The Ojibwe language and other members of the Algonquian languages distinguish between animate and inanimate classes. Some sources argue that the distinction is between things which are powerful and things which are not. All living things, as well as sacred things and things connected to the Earth are considered powerful and belong to the animate class. Still, the assignment is somewhat arbitrary, as "raspberry" is animate, but "strawberry" is inanimate.
Athabaskan languages 
In Navajo (Southern Athabaskan) nouns are classified according to their animacy, shape, and consistency. Morphologically, however, the distinctions are not expressed on the nouns themselves, but on the verbs of which the nouns are the subject or direct object. For example, in the sentence Shi’éé’ tsásk’eh bikáa’gi dah siłtsooz "My shirt is lying on the bed", the verb siłtsooz "lies" is used because the subject shi’éé’ "my shirt" is a flat, flexible object. In the sentence Siziiz tsásk’eh bikáa’gi dah silá "My belt is lying on the bed", the verb silá "lies" is used because the subject siziiz "my belt" is a slender, flexible object. See Navajo language: Classificatory Verbs for more discussion.
Koyukon (Northern Athabaskan) has a more intricate system of classification. Like Navajo, it has classificatory verb stems that classify nouns according to animacy, shape, and consistency. However, in addition to these verb stems, Koyukon verbs have what are called "gender prefixes" that further classify nouns. That is, Koyukon has two different systems that classify nouns: (a) a classificatory verb system and (b) a gender system. To illustrate, the verb stem -tonh is used for enclosed objects. When -tonh is combined with different gender prefixes, it can result in daaltonh which refers to objects enclosed in boxes or etltonh which refers to objects enclosed in bags.
Australian Aboriginal languages 
- I — animate objects, men
- II — women, water, fire, violence
- III — edible fruit and vegetables
- IV — miscellaneous (includes things not classifiable in the first three)
The class usually labeled "feminine", for instance, includes the word for fire and nouns relating to fire, as well as all dangerous creatures and phenomena. (This inspired the title of the George Lakoff book Women, Fire, and Dangerous Things.)
The Ngangikurrunggurr language has noun classes reserved for canines, and hunting weapons, and the Anindilyakwa language has a noun class for things that reflect light. The Diyari language distinguishes only between female and other objects. Perhaps the most noun classes in any Australian language are found in Yanyuwa, which has 16 noun classes, including nouns associated with food, trees and abstractions, in addition to separate classes for men and masculine things, women and feminine things. In the men's dialect, the classes for men and for masculine things have simplified to a single class, marked the same way as the women's dialect marker reserved exclusively for men.
Caucasian languages 
Some members of the Northwest Caucasian family, and almost all of the Northeast Caucasian languages, manifest noun class. In the Northeast Caucasian family, only Lezgian, Udi, and Aghul do not have noun classes. Some languages have only two classes, while the Bats language has eight. The most widespread system, however, has four classes: male, female, animate beings and certain objects, and finally a class for the remaining nouns. The Andi language has a noun class reserved for insects.
In all Caucasian languages that manifest class, it is not marked on the noun itself but on the dependent verbs, adjectives, pronouns and prepositions.
Niger–Congo languages 
Niger–Congo languages can have ten or more noun classes, defined according to non-sexual criteria. Certain nominal classes are reserved for humans. The Fula language has about 26 noun classes (exact number varies slightly by dialect). According to Steven Pinker, the Kivunjo language has 16 noun classes including classes for precise locations and for general locales, classes for clusters or pairs of objects and classes for the objects that come in pairs or clusters, and classes for abstract qualities.
Bantu languages 
According to Carl Meinhof, the Bantu languages have a total of 22 noun classes called nominal classes (this notion was introduced by W.H.J. Bleek). While no single language is known to express all of them, most of them have at least 10 noun classes. For example, by Meinhof's numbering, Shona has 20 classes, Swahili has 15, Sotho has 18 and Ganda has 17.
Specialists in Bantu emphasize that there is a clear difference between genders (such as known from Afro-Asiatic and Indo-European) and nominal classes (such as known from Niger–Congo). Languages with nominal classes divide nouns formally on the base of hyperonymic meanings. The category of nominal class replaces not only the category of gender, but also the categories of number and case.
Critics of the Meinhof's approach notice that his numbering system of nominal classes counts singular and plural numbers of the same noun as belonging to separate classes. This seems to them to be inconsistent with the way other languages are traditionally considered, where number is orthogonal to gender (according to the critics, a Meinhof-style analysis would give Ancient Greek 9 genders). If one follows broader linguistic tradition and counts singular and plural as belonging to the same class, then Swahili has 8 or 9 noun classes, Sotho has 11 and Ganda has 10.
The Meinhof numbering tends to be used in scientific works dealing with comparisons of different Bantu languages. For instance, in Swahili the word rafiki ‘friend’ belongs to the class 9 and its "plural form" is marafiki of the class 6, even if most nouns of the 9 class have the plural of the class 10. For this reason, noun classes are often referred to by combining their singular and plural forms, e.g., rafiki would be classified as "9/6", indicating that it takes class 9 in the singular, and class 6 in the plural.
However not all Bantu languages have these exceptions. In Ganda each singular class has a corresponding plural class (apart from one class which has no singular–plural distinction; also some plural classes correspond to more than one singular class) and there are no exceptions as there are in Swahili. For this reason Ganda linguists use the orthogonal numbering system when discussing Ganda grammar (other than in the context of Bantu comparative linguistics), giving the 10 traditional noun classes of that language.
The distinction between genders and nominal classes is blurred still further by Indo-European languages that have nouns that behave like Swahili's rafiki. Italian, for example, has a group of nouns deriving from Latin neuter nouns that acts as masculine in the singular but feminine in the plural: il braccio/le braccia; l'uovo/le uova. (These nouns are still placed in a neuter gender of their own by some grammarians.)
Here is a complete list of nominal classes in Swahili:
|Class number||Prefix||Typical meaning|
|1||m-, mw-, mu-||singular: persons|
|2||wa-, w-||plural: persons (a plural counterpart of class 1)|
|3||m-, mw-, mu-||singular: plants|
|4||mi-, my-||plural: plants (a plural counterpart of class 3)|
|5||ji-, j-, Ø-||singular: fruits|
|6||ma-, m-||plural: fruits (a plural counterpart of class 5, 9, 11, seldom 1)|
|7||ki-, ch-||singular: things|
|8||vi-, vy-||plural: things (a plural counterpart of class 7)|
|9||n-, ny-, m-, Ø-||singular: animals, things|
|10||n-, ny-, m-, Ø-||plural: animals, things (a plural counterpart of class 9 and 11)|
|11||u-, w-, uw-||singular: no clear semantics|
|15||ku-, kw-||verbal nouns|
|16||pa-||locative meanings: close to something|
|17||ku-||indefinite locative or directive meaning|
|18||mu-, m-||locative meanings: inside something|
Class prefixes appear also on adjectives and verbs, e.g.:
- Kitabu kikubwa kinaanguka. (cl.7-book cl.7-big cl.7-PRESENT-fall)
- ‘The big book falls.’
The class markers which appear on the adjectives and verbs may differ from the noun prefixes:
- Mtoto wangu alikinunua kitabu. (cl.1-child cl.1-my cl.1-PAST-cl.7-buy cl.7-book)
- ‘My child bought a book.’
In this example, the verbal prefix a- and the pronominal prefix wa- are in concordance with the noun prefix m-: they all express class 1 despite of their different forms.
There are about 80 inanimate nouns which are in the animate class, including nouns denoting heavenly objects (moon, rainbow), metal objects (hammer, ring), edible plants (sweet potato, pea), and non-metallic objects (whistle, ball). Many of the exceptions have a round shape, and some can be explained by the role they play in Zande mythology.
Noun classes versus grammatical genders 
The term gender, as used by some linguists, refers to a noun-class system composed with 2, 3, or 4 classes, particularly if the classification is semantically based on a distinction between masculine and feminine. Genders are then considered a sub-class of noun classes. Not all linguists recognize a distinction between noun-classes and genders, however, and instead use either the term "gender" or "noun-class" for both.
In languages with genders, the gender is a selective category for nouns. This means that all nouns must be assigned to a gender, and thus all nouns may be divided into groups, considering their gender. For instance, the Polish word ręcznik ‘towel’ is of inanimate masculine gender, whereas words for male human beings and animals belong to the personal masculine and animate masculine genders respectively; encyklopedia ‘encyclopaedia’ is of feminine gender, which includes words for female human beings and animals; and krzesło ‘chair’ is of neuter gender, which includes words for neuter animals and the word 'child'. The word "gender" derives from Latin genus, which is also the root of genre, and originally meant "kind", so it does not necessarily have a sexual meaning. For instance, in Swedish nouns are either of common or neuter gender; words for both males and females are assigned to common.
A language is mostly considered to have grammatical gender when changes in the gender of a noun necessarily induce morphological changes in adjectives and other parts of speech (such as verbs) that refer to that noun. For adjective and some other inflecting words, gender is an inflected category. It means that (in languages with genders) adjectives are inflected by genders, or change their forms depending on gender of the noun to which they refer. In yet other words, when a noun belongs to a certain gender, other parts of speech that refer to that noun have to be inflected to be in the same class. These obligatory changes are called gender agreement.
In Polish, the adjective which means ‘big, large’ has three forms (in nominative singular), one for masculine, one for feminine, and one for neuter gender: duży ręcznik ‘big towel’, duża encyklopedia ‘big encyclopaedia’, duże krzesło ‘big chair’.
Noun classes versus noun classifiers 
Some languages, such as Japanese, Chinese and the Tai languages, have elaborate systems of particles which classify nouns based on shape and function, but are free morphemes rather than affixes. Because the classes defined by these classifying words are not generally distinguished in other contexts, many if not most linguists take the view that they do not create grammatical genders.
List of languages by type of noun classification 
Languages with noun classes 
- all Bantu languages such as
- Ganda: ten classes called simply Class I to Class X and containing all sorts of arbitrary groupings but often characterised as people, long objects, animals, miscellaneous objects, large objects and liquids, small objects, languages, pejoratives, infinitives, mass nouns, plus four 'locative' classes. Alternatively, the Meinhof system of counting singular and plural as separate classes gives a total of 21 classes including the four locatives.
- Dyirbal: Masculine, feminine, vegetal and other. (Some linguists do not regard the noun-class system of this language as grammatical gender.)
- Fula (Fulfulde, Pulaar, Pular)
Languages with grammatical genders 
See also 
- Classifier (linguistics)
- Grammatical agreement
- Grammatical category
- Grammatical conjugation
- Grammatical gender
- Grammatical number
- Redundancy (linguistics)
- Synthetic language
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