why

English Wikipedia has an article on:

why

Wikipedia

From Middle English why, from Old English hwȳ (“why”), from Proto-Germanic *hwī (“by what, how”), from Proto-Indo-European *kʷey, instrumental case of *kʷis (“who”), *kʷid (“what”).

Cognate with Old Saxon hwī (“why”), hwiu (“how; why”), Middle High German wiu (“how, why”), archaic Danish and Norwegian Bokmål hvi (“why”), Norwegian Nynorsk kvi (“why”), Swedish vi (“why”), Faroese and Icelandic hví (“why”), Latin quī (“why”), Doric Greek πεῖ (peî, “where”), Ukrainian чи (čy, “if”), Polish czy, Czech či (“or”), Serbo-Croatian či (“if”). Compare Old English þȳ (“because, since, on that account, therefore, then”, literally “by that, for that”). See thy.

• enPR: hwī, wī, IPA^(key): /waɪ/, /ʍaɪ/

• Audio (US, without the wine–whine merger):

  (file)

• Audio (US, wine–whine merger):

  (file)

• Audio (UK, wine–whine merger):

  (file)

• Rhymes: -aɪ
• Homophones: wye, Y, y (wine–whine merger)

why (not comparable)

1. (interrogative) For what cause, reason, or purpose.
   1. Introducing a complete question.

      Why is the sky blue?

      Why did you do that?

      I don’t know why he did that

      Tell me why the moon changes phase.

      • 2016, VOA Learning English (public domain)

        Why do you have a map of the world?

        Audio (US):

        (file)

      1. With a negative, used rhetorically to make a suggestion.

         Why don't you ask her out for dinner?

   2. Introducing a verb phrase (bare infinitive clause).

      Why spend money on something you already get for free?

      Why not tell him how you feel?

   3. Introducing a noun or other phrase.

      Why him? Why not someone taller?

2. (relative) For which cause, reason, or purpose.

   That's the reason why I did that.

3. (fused relative) The cause, reason, or purpose for which.

   That is why the sky is blue.

   • 2013 July 20, “Welcome to the plastisphere”, in The Economist, volume 408, number 8845:

     Plastics are energy-rich substances, which is why many of them burn so readily. Any organism that could unlock and use that energy would do well in the Anthropocene. Terrestrial bacteria and fungi which can manage this trick are already familiar to experts in the field.

• how come, wherefore, to what end, what for, why so, (obsolete) for why

why (plural whys or why's or whies)

1. Reason.

   A good article will cover the who, the what, the when, the where, the why and the how.

   • 2022 May 11, Sandra E. Garcia, “Butt Lifts Are Booming. Healing Is No Joke.”, in The New York Times Magazine‎^[1]:

     Within months of leaving, she became the new owner of Dream Body Recovery in Miami, which has three rooms that can accommodate up to six clients. “Being a part of this journey with other ladies, knowing how it changed my life, that’s my why,” she told me.

• wherefore

why

1. (dated or literary) An exclamation used to express pleasant or unpleasant mild surprise, indignation, or impatience.

   Why, that’s ridiculous!    Why, how kind of you!

   • 1724, [Daniel Defoe], The Fortunate Mistress; […] [Roxana], London: […] E. Applebee, […], published 1740, →OCLC, page 242:

     VVhy Child, I tell thee if I vvas thy Mmother I ſhould not diſovvn thee; Don't you ſee I am as kind to you as if I vvas your Mother?

why (third-person singular simple present whys or whies, present participle whying, simple past and past participle whyed or whied)

1. (intransitive, transitive) To ask (someone) the question "why?".
   • 1930, D[avid] H[erbert] Lawrence, Assorted Articles, London: Martin Secker, page 11:

     Why indeed? But once you start whying, there's no end to it.

why (plural whies)

1. (UK, dialect, archaic) A young heifer.
   • 1796, William Marshall, The Rural Economy of Yorkshire:

     At two years old, also, the HEIFERS - provincially, “whies,” are generally put to the bull.

why

1. Alternative form of wye; the name of the Latin-script letter Y/y.
   • 1881 April, J. B. Rundell, “The Irregularities of English Spelling: what they Cost and what they are Worth”, in The Spelling Reformer, and Journal of the English Spelling Reform Association, volume I, number 10, London, page 147:

     ee, why, ee, ess, eyes

   • 1996, Sycamore Review, volume 8, page 116:

     eff you see kay why oh you.

   • 2009, Eric Barnes, Shimmer, Denver, Colo.: Unbridled Books, →ISBN, page 91:

     I hear you. But hear me out, all right? Because I mean what I’m about to say. Eff-you-see-kay-why-oh-you. Fuck you.

   • 2016, Daniel DiPrinzio, “Come Quickly”, in The Great Stone Robbery or A Parade of Idiots, →ISBN, page 184:

     Like many folks do when taking medicine past its expiration date, Jerry had questioned its effectiveness. The pill had answered with a resounding why ee ess, and Jerry couldn’t tell between the Custom Costume in his pocket and himself.

   • 2016, Rachel Cohn, David Levithan, The Twelve Days of Dash & Lily, Electric Monkey, →ISBN, page 73:

     Miss said, “Love your outfit, bee-tee-double-u.” It took me a second to realize she meant “btw.” “Is it vintage?” / I looked down at my school uniform. Fudgsicles. “Tee-why,” said Jahna, for “ty.” “And why-ee-ess yes!”

• “why, v.”, in OED Online ⁠, Oxford: Oxford University Press, launched 2000.

• “why”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.
• “why”, in The Century Dictionary […], New York, N.Y.: The Century Co., 1911, →OCLC.

• hwy, hwy.

• hwi (Standard Written Form)

From Proto-Celtic *swīs (compare Breton c’hwi, Welsh chi, Old Irish síi), from Proto-Indo-European *wos.

• IPA^(key): /ʍiː/, /ʍəɪ/

why

1. (Standard Cornish, Standard Written Form with Traditional Graphs) you (formal or plural)