why

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”), Ancient Greek πεῖ (peî, “where”). Compare Old English þȳ (“because, since, on that account, therefore, then”, literally “by that, for that”). See thy.

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

• Audio (US)

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  (in accents without the "wine-whine" merger)

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  (in accents with the "wine-whine" merger)

• Audio (UK)

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  (in accents with the "wine-whine" merger)
• Rhymes: -aɪ
• Homophones: wye, Y, y (all only in accents with the 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)

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      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

why (plural whys or why's)

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:

     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, Roxana: The Fortunate Mistress

     “Why, child, I tell thee if I was thy mother I would not disown thee; don't you see I am as kind to you as if I was your mother?”

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 in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913
• why in The Century Dictionary, New York, N.Y.: The Century Co., 1911

• 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)