adverb for what? for what reason, cause, or purpose?: Why did you behave so badly? conjunction for what cause or reason: I don't know why he is leaving. for which; on account of which (usually after reason to introduce a relative clause): the reason why he refused to go. the reason for which: That is why he returned. noun, plural whys. a question concerning the cause or reason for which something is done, achieved, etc.: a child's unending hows and whys. the cause or reason: the whys and wherefores of a troublesome situation. interjection (used as an expression of surprise, hesitation, etc., or sometimes a mere expletive): Why, it's all gone! Origin of why before 900; Middle English; Old English hwī, hwȳ,
instrumental case of
; cognate with
Old Norse hvī contraction of why is: Why's dinner so late?
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for why adverb for what reason, purpose, or cause? why are you here? ( used in indirect questions) tell me why you're here pronoun for or because of which there is no reason why he shouldn't come noun plural whys (usually plural) the reason, purpose, or cause of something (esp in the phrase the whys and wherefores) interjection an introductory expression of surprise, disagreement, indignation, etc why, don't be silly! Word Origin for why
hwī; related to Old Norse hvī, Gothic hveileiks what kind of, Latin quī
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
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Word Origin and History for why
hwi, instrumental case (showing for what purpose or by what means) of hwæt (see what), from Proto-Germanic *khwi (cf. Old Saxon hwi, Old Norse hvi), from PIE *qwei, locative of *qwo- "who" (cf. Greek pei "where"). As an interjection of surprise or to call attention to a statement, recorded from 1510s.
Online Etymology Dictionary, © 2010 Douglas Harper