Origin of why

before 900; Middle English; Old English hwī, hwȳ, instrumental case of hwæt what; cognate with Old Norse hvī

Usage note

See reason.

why's

[hwahyz, wahyz]

contraction of why is: Why's dinner so late?

Usage note

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Related Words for why

motive, mystery, cause, proof, how

British Dictionary definitions for why

why

adverb

  1. for what reason, purpose, or cause?why are you here?
  2. (used in indirect questions)tell me why you're here

pronoun

for or because of whichthere 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, etcwhy, don't be silly!

Word Origin for why

Old English hwī; related to Old Norse hvī, Gothic hveileiks what kind of, Latin quī
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for why

Old English 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