The nominal categorization of grammatical gender (genus) is considered to exist in a language if agreement depends on the nominal class of a given noun.[1] Sites of agreement may include verbs, adjectives, determiners, numerals, and focus markers. In some languages, the gender system applies only to anaphoric pronouns.[2]

Types:

NoGns: Grammatical gender (the categorization of nouns into grammatical classes) does not exist.

Gns2: Nouns fall into two genders for the purpose of agreement.

Gns3: Nouns fall into three genders for the purpose of agreement.

Gns4: Nouns fall into four genders for the purpose of agreement.

Gns+4: Nouns fall into five or more genders for the purpose of agreement.

[1] The class a noun belongs to can only be determined by looking beyond the noun itself to its environment. For this reason, examination of the noun’s affixation is not sufficient evidence to determine its gender. When pairs of separate words exist to describe men and women, agreement is still required to ascertain the gender of these words, even if the words differ in their roots or derivation. Grammatical gender should not be confused with classifiers (as in head in five heads of cattle), since the latter category does not require agreement.

[2] This is a rare occurrence, and English is one such example.