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

Hunt was the intellectual anchor of that leg, which is why his resignation is news.

From MarketWatch ● Jul. 27, 2026

The toughness of these larvae suggests that pressure alone may not fully explain why insects never established themselves throughout the ocean.

From Science Daily ● Jul. 27, 2026

What is nitrous oxide and why is it being banned?

From BBC ● Jul. 27, 2026

That history is why contesting the constitutional allocation of public safety cannot mean giving private people authority to govern vulnerable people.

From Slate ● Jul. 27, 2026

“If you’re so worried, why don’t you ask him?”

From "Red Flags and Butterflies" by Sheryl Azzam

One note for Miles, like Billie Holiday, like Cindy says, that’s enough to understand all the whys and all the reasons why it’s sacred to be alive.

From Los Angeles Times ● May 25, 2026

"Why did no-one tell the young people to get out? Why did the council not make the proper checks? There are too many whys."

From BBC ● Jan. 9, 2026

You don't know the whos and the whats and the whys of how we came to be and how our relationship fell apart to get us to that point.

From Salon ● Oct. 26, 2024

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 will keep my chin up and hopefully resume writing all the whos, whats, whys, whens, and wheres by next week.

From "Moon Over Manifest" by Clare Vanderpool