why

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

• Audio (US)

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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. For what cause, reason, or purpose (interrogative adverb).
   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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   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. For which cause, reason, or purpose (relative adverb).

   That's the reason why I did that.

   • 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

why (plural whys)

1. reason

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

• wherefore

why

1. An exclamation used to express indignation, mild surprise, or impatience.
   • Daniel Defoe

     “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. (Britain, dialectal) A young heifer.

   (Can we find and add a quotation of Grose to this entry?)

• 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.

• IPA^(key): /ʍiː/, /ʍəɪ/

why

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