1
: the cause, reason, or purpose for which
know why you did it
that is why you did it
2
: for which : on account of which
know the reason why you did it
plural whys
—used to express mild surprise, hesitation, approval, disapproval, or impatience
why, here's what I was looking for
Examples of why in a Sentence
Adverb
Why did you quit your job?
Why is the sky blue?
Why didn't you call me?
Why didn't I think of that?
“I can't go out tonight.” “Why not?”
Conjunction
I know why he did it.
It's easy to see why she fell in love with him.
He's a very good player. That's why he made the team.
The reason why they succeeded is obvious. They worked really hard.
Give me one good reason why I should stay.
Noun
asked the whys behind the surprising decision
how one decides that a certain he or she is “the one” is one of the great whys of life
Interjection
why, what a strange thing to say!
Recent Examples on the Web
Jem Aswad, Variety, 2 Nov. 2023
Several wanted to know why the Chinese airship was allowed to float all the way to the Atlantic Ocean before it was shot down.
—Ellen Nakashima, Washington Post, 11 Feb. 2023
Zoya Hasan, Forbes.com, 23 May 2025
The why: Dazzling September debut quickly escalated expectations that the hard-throwing lefty will become a major bullpen weapon.
—Marc Topkin, The Orlando Sentinel, 26 Mar. 2025
Filip Bondy, New York Times, 30 Apr. 2017
See All Example Sentences for why
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Adverb
So that’s the how and why; the real — unfair — question is whether the song comes close to measuring up to the Beatles or their collective solo works’ towering legacy.
—Jem Aswad, Variety, 2 Nov. 2023
Several wanted to know why the Chinese airship was allowed to float all the way to the Atlantic Ocean before it was shot down.
—Ellen Nakashima, Washington Post, 11 Feb. 2023
Noun
Build your own opportunities, document your journey, and stay rooted in your why.
—Zoya Hasan, Forbes.com, 23 May 2025
The why: Dazzling September debut quickly escalated expectations that the hard-throwing lefty will become a major bullpen weapon.
—Marc Topkin, The Orlando Sentinel, 26 Mar. 2025
Interjection
Why, oh why, do the Rangers keep throwing away almost certain victories in the final minutes of playoff games?
—Filip Bondy, New York Times, 30 Apr. 2017
See All Example Sentences for why
Cite this Entry
“Why.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/why. Accessed 11 Jul. 2025.
Copy CitationKids Definition
why
1 of 4 adverb
(ˈ)hwī 
(ˈ)wī
: for what cause or reason
why did you do it
why
2 of 4 conjunction1
: the cause or reason for which
know why you did it
2
: for which : on account of which
the reason why she did it
why
3 of 4 nounˈhwī,
ˈwī
plural whys
: reason entry 1 sense 1a
explained the whys and wherefores of the sudden price increase
why
4 of 4 interjection(ˌ)wī,
(ˌ)hwī
—used to express surprise, indecision, approval, disapproval, or impatience
why, I didn't know that
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