1 — used as an interrogative expressing inquiry about the identity, nature, or value of an object or matter (2) — often used to ask for repetition of an utterance or part of an utterance not properly heard or understood
2. (1) archaic; who 1 — used as an interrogative expressing inquiry about the identity of a person (2) — used as an interrogative expressing inquiry about the character, nature, occupation, position, or role of a person
3 — used as an exclamation expressing surprise or excitement and frequently introducing a question
4 — used in expressions directing attention to a statement that the speaker is about to make
5 (1) — used at the end of a question to express inquiry about additional possibilities (2) — used with or at the end of a question usually in expectation of agreement
6 chiefly British — used at the end of an utterance as a form of tag question
A relative pronoun referring to a subject or direct object.