In linguistics and grammar, a pronoun (abbreviated PRO) is a word or a group of words that one may substitute for a noun or noun phrase.

Pronouns have traditionally been regarded as one of the parts of speech, but some modern theorists would not consider them to form a single class, in view of the variety of functions they perform cross-linguistically. An example of a pronoun is "you", which can be either singular or plural. Subtypes include personal and possessive pronouns, reflexive and reciprocal pronouns, demonstrative pronouns, relative and interrogative pronouns, and indefinite pronouns.^: 1–34

The use of pronouns often involves anaphora, where the meaning of the pronoun is dependent on an antecedent. For example, in the sentence That poor man looks as if he needs a new coat, the meaning of the pronoun he is dependent on its antecedent, that poor man.

The name of the adjective that belongs with a "pronoun" is called a "pronominal". A pronominal is also a word or phrase that acts as a pronoun. For example, in That's not the one I wanted, the phrase the one (containing the prop-word one) is a pronominal.