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

• whys
  plural

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.

Other Word Forms

Noun Inflected Forms

• whys
  plural

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

See Examples For:

why whys

“DCOR is the poster child for why the Coastal Commission must retain its … ability to challenge yet another very bad idea that will increase the risk of a spill off our coast.”

From Los Angeles Times ● Aug. 14, 2026

"I think that's why they didn't let me and Yabloko run," he added.

From Barron's ● Aug. 14, 2026

If transportation is universally available without fares on campus, it may seem natural to ask why urban transportation doesn’t function similarly.

From The Wall Street Journal ● Aug. 14, 2026

O'Neill understood why Engels was keen to complete the transfer, especially after Canada right-back Alistair Johnston - who had attracted interest from Everton - suffered a leg muscle injury.

From BBC ● Aug. 14, 2026

"Sancho, Sancho, you're beginning to sound like your master. Of course we understand. That's why we want both of you to go back home. There are wrongs to right at home, too," the priest said.

From "Adventures of Don Quixote" by Argentina Palacios

Appearing before the Democratic faithful at the state party convention in San Francisco, hopefuls offered the whys and wherefore of their candidacies.

From Los Angeles Times ● Mar. 8, 2026

"We have decided to study in great detail the hows and whys of why premature birth affects the developing brain," he says.

From BBC ● Apr. 8, 2025

The hows are easier to explain than the whys when it comes to all this madness, so let’s start there.

From Salon ● Nov. 7, 2023

Physicists believe that there must have been some primordial imbalance that allowed matter to dominate the universe, yet the hows and whys remain open questions.

From Scientific American ● Sep. 27, 2023

I do not want to hear your whys, Uhmma insists.

From "A Step from Heaven" by An Na