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 there he was, ready to race in the desert, within striking distance of his two McLaren rivals—and Verstappen wanted to remind them why.

From The Wall Street Journal

He noted that one idea about why animals might seek out ethanol is that its smell helps them locate foods that are richer in sugar and thus provide more energy.

From Science Daily

He did not say why he was being seen at Walter Reed, but an official memo said he was present to “visit” with service members and conducted a “planned meeting.”

From Salon

He added: "I didn't want to breach the manifesto, and that's why we came to the decisions that we did."

From BBC

College Football Brain is why we still have Zombie Bowl games layered on top of this 12-team playoff, as if anyone actually cares or comprehends why the quarterfinal needs to masquerade as the Cotton Bowl.

From The Wall Street Journal