A noun may belong to a given class because of the characteristic features of its referent, such as gender, animacy, shape, but such designations are often clearly conventional.
Some authors use the term "grammatical gender" as a synonym of "noun class", but others consider these different concepts.
The choice between the relative pronoun who (persons) and which (non-persons) may also be considered a form of agreement with a semantic noun class.
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.
Like Navajo, it has classificatory verb stems that classify nouns according to animacy, shape, and consistency.
The Dyirbal language is well known for its system of four noun classes, which tend to be divided along the following semantic lines:[2] 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.)
Among Northwest Caucasian languages, only Abkhaz and Abaza have noun class, making use of a human male/human female/non-human distinction.
In all Caucasian languages that manifest class, it is not marked on the noun itself but on the dependent verbs, adjectives, pronouns and postpositions or prepositions.
The Fula language has about 26 noun classes (the exact number varies slightly by dialect).
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 Meinhof numbering tends to be used in scientific works dealing with comparisons of different Bantu languages.
The distinction between genders and nominal classes is blurred still further by Indo-European languages that have nouns that behave like Swahili's rafiki.
'The class markers which appear on the adjectives and verbs may differ from the noun prefixes: MtotoCL1-childwanguCL1-myalinunuaCL1-PST-CL7-buykitabu.CL7-bookMtoto wangu alinunua kitabu.CL1-child CL1-my CL1-PST-CL7-buy CL7-book'My child bought a book.
Many of the exceptions have a round shape, and some can be explained by the role they play in Zande mythology.
The term "gender", as used by some linguists, refers to a noun-class system composed with two, three, or four classes, particularly if the classification is semantically based on a distinction between masculine and feminine.