Synonyms

why

American

[hwahy, wahy] / ʰwaɪ, waɪ /

adverb

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

Why did you behave so badly?

conjunction

for what cause or reason.

I don't know why he is leaving.
for which; on account of which (usually after reason to introduce a relative clause).

the reason why he refused to go.
the reason for which.

That is why he returned.

noun

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

a child's unending hows and whys.
the cause or reason.

the whys and wherefores of a troublesome situation.

interjection

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

Why, it's all gone!

why British

/ waɪ /

adverb

1. for what reason, purpose, or cause?
  
  why are you here?
2. ( used in indirect questions )
  
  tell me why you're here

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

pronoun

for or because of which

there is no reason why he shouldn't come

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

interjection

an introductory expression of surprise, disagreement, indignation, etc

why, don't be silly!

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Usage

See reason.

Other Word Forms

Inflected Forms

noun

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

Vocabulary lists containing why

Scrabble: Words with no Vowels

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

When visitors reach the hilltop, they will find an upgraded Welcome Hall designed by local firm WHY Architecture, with new features including a large information screen and an expanded bookstore with its own café.

From Los Angeles Times • May 28, 2026

Even Gaiman questioned the nomination process, commenting on the post, “Is there anyone who could actually explain WHY 'Sandman' episode 6 was ineligible?”

From Salon • Feb. 16, 2024

Backyards are tiny and your neighbors probably don’t have air conditioning, so their windows are open … WHY?!

From Seattle Times • Aug. 16, 2023

Scientists have several ideas, but they're still not sure WHY humans seem to be able to understand ape gestures.

From NewsForKids.net • Feb. 23, 2023

The stranger was very clear we weren’t to take any more pictures, but didn’t explain WHY.

From "The Last Last-Day-of-Summer" by Lamar Giles

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023