Whom

Whom is a personal pronoun in English that serves as the object form of who. It refers to people and is used where the person is the recipient of an action or the object of a preposition. The possessive form of who is whose, which does not carry a separate possessive pronoun for whom.

In ordinary sentences, whom appears as the object of a verb: Whom did you see? In questions, did you see whom? is the formal variant, while Who did you see? is common in everyday speech. After prepositions, whom is standard: to whom, with whom, by whom, for whom. In informal style, many speakers end prepositional phrases with whom, producing structures like who you spoke with, though such endings are increasingly accepted in casual writing.

Whom also appears in relative clauses to mark the object of the clause: The woman whom you met is my aunt. In more formal style, the preposition can be placed before the relative pronoun: The woman to whom you spoke is my aunt. In everyday language, many speakers use who in place of whom in relative clauses, especially when the pronoun is the object.

Whom is part of a broader system that includes whomsoever and whomever, used in more formal or emphatic constructions: Whomever you choose will lead the team. Whom is also related to whose, the possessive form used for both people and things.

Summary: whom is the object pronoun of who, used after verbs and prepositions, in formal contexts and certain relative clauses, with who emerging as a common substitute in informal English.