A system of classes of nouns which trigger specific types of inflections in associated words.

A language may have two or more such classes or genders. The classification frequently corresponds to a real-world distinction of sex, at least in part, but often too it does not ("gender" derives etymologically from Lartin genus, via Old French gendre, and originally meant "kind" or "sort"). The word "gender" is used not just for a group of nouns but also for the whole category; thus we may say that a particular language has, say, three genders, masculine, feminine and neuter, and that the language has the category of gender.

Source: Gender.