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

“Shrinking the balance sheet may indeed be an argument Warsh leans into as to why rates should be lower,” said Mark Cabana, head of U.S. rates strategy at BofA Global Research.

From MarketWatch • Apr. 18, 2026

Or why OpenAI is racing to put a better spin on what it says its technology might one day do.

From The Wall Street Journal • Apr. 18, 2026

But I also understand the rage of taxpayers who wonder why Los Angeles City Hall is so incapable of managing the basics.

From Los Angeles Times • Apr. 18, 2026

Which brings us back to Carlson, who understands that major publishers aren’t a censoring force to be circumvented, which is why he has partnered with Skyhorse rather than trying to build something entirely from scratch.

From Salon • Apr. 18, 2026

I want to tell him all the reasons why we can’t take him.

From "Red Flags and Butterflies" by Sheryl Azzam