Etymology: Middle English, from Old English hwæt, neuter of hwā who — more at who
Date: before 12th century
(1) — used as an interrogative expressing inquiry about the identity, nature, or value of an object or matter <what is this> <what is wealth without friends> <what does he earn> <what hath God wrought> (2) — often used to ask for repetition of an utterance or part of an utterance not properly heard or understood <you said what> b. (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 <what do you think I am, a fool> <what is she, that all our swains commend her — Shakespeare> c. — used as an exclamation expressing surprise or excitement and frequently introducing a question <what, no breakfast> d. — used in expressions directing attention to a statement that the speaker is about to make <you know what> e. (1) — used at the end of a question to express inquiry about additional possibilities <is it raining, or snowing, or what> (2) — used with or at the end of a question usually in expectation of agreement <is this exciting, or what> f. chiefly British — used at the end of an utterance as a form of tag question <a clever play, what> 2. chiefly dialect that IV,1, which 3, who 3 3. a. that which ; the one or ones that <no income but what he gets from his writings> — sometimes used in reference to a clause or phrase that is yet to come or is not yet complete <gave also, what is more valuable, understanding> b. the thing or things that <what you need is a vacation> <what angered us was the tone of the article> 4. a. whatever 1a <say what you will> b. obsolete whoever II. adverb Date: before 12th century 1. obsolete why 2. in what respect ; how <what does he care> 3. — used to introduce prepositional phrases in parallel construction or a prepositional phrase that expresses cause and usually has more than one object; used principally before phrases beginning with with <what with unemployment increasing> <what with the war, what with the sweat, what with the gallows, and what with poverty, I am custom-shrunk — Shakespeare> III. adjective Date: 13th century 1. a. — used as an interrogative expressing inquiry about the identity, nature, or value of a person, object, or matter <what minerals do we export> b. how remarkable or striking for good or bad qualities — used especially in exclamatory utterances and dependent clauses <what mountains> <remember what fun we had> <what a suggestion> <what a charming girl> 2. a. (1) whatever 1a (2) any <ornament of what description soever> b. the…that ; as much or as many…as <rescued what survivors they found>
New Collegiate Dictionary. 2001.