Animacy is a grammatical and/or semantic category of nouns based on how sentient or alive the referent of the noun in a given taxonomic scheme is. Animacy can have various effects on the grammar of a language, such as choice of pronoun (what/who), case endings, word order, or the form a verb takes when it is associated with that noun.

In languages which demonstrate animacy, some have simple systems where nouns are either animate (e.g. people, animals) or inanimate (e.g. buildings, trees, abstract ideas), whereas others have complex hierarchical systems. In such a system, personal pronouns generally have the highest animacy (with the first person being highest among them), followed by other humans, animals, plants, natural forces such as wind, concrete objects, and abstractions, in that order. It is possible that different languages with animacy hierarchies could rank nouns in different ways; but because human languages have not all been thoroughly documented yet, it is impossible to generalise completely.