as an interrogative pronoun, used in asking questions regarding either persons or things; as, what is this? what did you say? what poem is this? what child is lost?-as an exclamatory word: -- (a) used absolutely or independently; -- often with a question following.-used adjectively, meaning how remarkable, or how great; as, what folly! what eloquence! what courage!-sometimes prefixed to adjectives in an adverbial sense, as nearly equivalent to how; as, what happy boys!-as a relative pronoun-used substantively with the antecedent suppressed, equivalent to that which, or those [persons] who, or those [things] which; -- called a compound relative.-used adjectively, equivalent to the . . . which; the sort or kind of . . . which; rarely, the . . . on, or at, which.-used adverbially in a sense corresponding to the adjectival use; as, he picked what good fruit he saw.-whatever; whatsoever; what thing soever; -- used indefinitely.-used adverbially, in part; partly; somewhat; -- with a following preposition, especially, with, and commonly with repetition.-something; thing; stuff.-why? for what purpose? on what account?