In many languages every noun belongs to a class that affects agreement. Grammatical gender is a system that categorizes nouns into groups—such as masculine, feminine, and neuter—requiring matching forms on associated words.

Gender assignment may correlate loosely with biological sex for some animate nouns but is largely arbitrary for inanimates. Articles, adjectives, and pronouns often display gender agreement. Languages without grammatical gender still express social gender through vocabulary and pronouns.

Gender systems change historically through reanalysis and contact. They pose well-known challenges for second-language learners and for natural language processing. Descriptive grammars specify both the inventory of genders and the rules of assignment and agreement.

• Grammatical noun-class system affecting agreement
• Often labeled masculine, feminine, neuter, or similar
• Assignment only partly semantic
• Distinct from social gender though sometimes linked