why

American  

[hwahy, wahy] / ʰwaɪ, waɪ /

adverb

1. for what? for what reason, cause, or purpose?.

   Why did you behave so badly?

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conjunction

1. for what cause or reason.

   I don't know why he is leaving.

2. for which; on account of which (usually after reason to introduce a relative clause).

   the reason why he refused to go.

3. the reason for which.

   That is why he returned.

noun

plural

whys

1. a question concerning the cause or reason for which something is done, achieved, etc..

   a child's unending hows and whys.

2. the cause or reason.

   the whys and wherefores of a troublesome situation.

interjection

1. (used as an expression of surprise, hesitation, etc., or sometimes a mere expletive).

   Why, it's all gone!

why British  

/ waɪ /

adverb

1. 1. for what reason, purpose, or cause?

      why are you here?

   2. ( used in indirect questions )

      tell me why you're here

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pronoun

1. for or because of which

   there is no reason why he shouldn't come

noun

1. (usually plural) the reason, purpose, or cause of something (esp in the phrase the whys and wherefores )

interjection

1. an introductory expression of surprise, disagreement, indignation, etc

   why, don't be silly!

Usage

See reason.

Etymology

Origin of why

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

Example Sentences

But why is Northern Ireland's fuel prices coming down?

From BBC

"That is why we work so hard in the week to try and do that."

From BBC

"And I almost feel like that, to the full extent, has been taken away from me, because right now I can't do those things, and I've got to explain to my children why."

From BBC

He was always prepared to gamble in order to get a desired outcome and felt it was why he enjoyed so many late successes in his stellar career.

From BBC

This is probably why so many passengers spent a lot of time in the water.

From The Wall Street Journal