What does 理由 (riyuu | りゆう) mean in Japanese?

The Japanese word

理由は誰も分からない。
riyū wa dare mo wakara nai.
No one can tell the reason. | No one knows the reason. | Nobody knows why.

理由がわかりかねます。
riyū ga wakari kane masu.
I fail to see the reason.

彼女はある理由で来なかった。
kanojo wa aru riyū de ko nakatta.
She did not come for a certain reason.

彼女が来ない理由が解らない。
kanojo ga ko nai riyū ga wakara nai.
I don't know the reason why she isn't coming.

本学に入学したい理由は何ですか。
hongaku ni nyūgaku shi tai riyū wa nani desu ka.
What is the reason you want to enter this college?

彼女は遅くなった理由を説明した。
kanojo wa osoku natta riyū o setsumei shi ta.
She explained the reason why she was late.

彼女は何かの理由で仕事をやめた。
kanojo wa nani ka no riyū de shigoto o yame ta.
She quit her job for some reason.

彼女が怒った理由を教えて下さい。
kanojo ga okotta riyū o oshie te kudasai.
Please tell me the reason why she got angry.

彼女は遅れてきた理由を言わなかった。
kanojo wa okure te ki ta riyū o iwa nakatta.
She didn't mention the reason for being late.

彼女と結婚した理由を話してください。
kanojo to kekkon shi ta riyū o hanashi te kudasai.
Tell me the reason why you married her.

別の理由があるね？どう？図星でしょう？
betsu no riyū ga aru ne? dō? zuboshi desho u?
There's another reason, isn't there? Well, how did I do? I bet I hit the mark.

理由はなんにせよ彼らは結婚しなかった。
riyū wa nan ni seyo karera wa kekkon shi nakatta.
Whatever the reason, they did not marry.

彼女が逮捕された理由を説明して下さい。
kanojo ga taiho sa re ta riyū o setsumei shi te kudasai.
Please explain the reason why she was arrested.

彼女の申し出を受けていけない理由はない。
kanojo no mōshide o uke te ike nai riyū wa nai.
I see no reason why I shouldn't accept her offer.

彼女が来られなかった理由を知っていますか。
kanojo ga ko rare nakatta riyū o shitte i masu ka.
Do you know the reason which prevented her from coming? | Do you know why she couldn't come?

彼女にはそうする理由がなかったと私は思った。
kanojo ni wa sō suru riyū ga nakatta to watashi wa omotta.
She had, I thought, no reason to do what she did.

父が医者だからといって僕も医者にならなければならぬ理由はない。
chichi ga isha da kara to itte boku mo isha ni nara nakere ba nara nu riyū wa nai.
There's no reason why I should become a physician because my father is one.

兄弟とも「妻と飛行機の両方は養えない」との理由で、生涯独身を通した。
kyōdai tomo ' tsuma to hikōki no ryōhō wa yashinae nai ' to no riyū de, shōgai dokushin o tōshi ta.
Saying they could not support both a wife and an airplane, the two brothers therefore spent their lives as bachelors. | Because they "could not both support wife and airplane" the two brothers spent their lives as bachelors. | Both brothers said that they couldn't support both a wife and an airplane, so they spent their lives as bachelors. | The reason both brothers gave for remaining bachelors was that they couldn't support both airplanes and a wife.

どんな理由があろうと、せっかく軌道に乗せた貿易を失墜させたのは大失態だ。
donna riyū ga aro u to, sekkaku kidō ni nose ta bōeki o shittsui sa se ta no wa dai shittai da.
Whatever the reason, forfeiting the trade that we finally got on track is a fiasco.

	The Japanese word
	理由
	is pronounced
	riyuu \| りゆう
	means
	reason, motive

	Examples:
	理由は誰も分からない。 riyū wa dare mo wakara nai. No one can tell the reason. \| No one knows the reason. \| Nobody knows why.
	理由がわかりかねます。 riyū ga wakari kane masu. I fail to see the reason.
	彼女はある理由で来なかった。 kanojo wa aru riyū de ko nakatta. She did not come for a certain reason.
	彼女が来ない理由が解らない。 kanojo ga ko nai riyū ga wakara nai. I don't know the reason why she isn't coming.
	本学に入学したい理由は何ですか。 hongaku ni nyūgaku shi tai riyū wa nani desu ka. What is the reason you want to enter this college?
	彼女は遅くなった理由を説明した。 kanojo wa osoku natta riyū o setsumei shi ta. She explained the reason why she was late.
	彼女は何かの理由で仕事をやめた。 kanojo wa nani ka no riyū de shigoto o yame ta. She quit her job for some reason.
	彼女が怒った理由を教えて下さい。 kanojo ga okotta riyū o oshie te kudasai. Please tell me the reason why she got angry.
	彼女は遅れてきた理由を言わなかった。 kanojo wa okure te ki ta riyū o iwa nakatta. She didn't mention the reason for being late.
	彼女と結婚した理由を話してください。 kanojo to kekkon shi ta riyū o hanashi te kudasai. Tell me the reason why you married her.
	別の理由があるね？どう？図星でしょう？ betsu no riyū ga aru ne? dō? zuboshi desho u? There's another reason, isn't there? Well, how did I do? I bet I hit the mark.
	理由はなんにせよ彼らは結婚しなかった。 riyū wa nan ni seyo karera wa kekkon shi nakatta. Whatever the reason, they did not marry.
	彼女が逮捕された理由を説明して下さい。 kanojo ga taiho sa re ta riyū o setsumei shi te kudasai. Please explain the reason why she was arrested.
	彼女の申し出を受けていけない理由はない。 kanojo no mōshide o uke te ike nai riyū wa nai. I see no reason why I shouldn't accept her offer.
	彼女が来られなかった理由を知っていますか。 kanojo ga ko rare nakatta riyū o shitte i masu ka. Do you know the reason which prevented her from coming? \| Do you know why she couldn't come?
	彼女にはそうする理由がなかったと私は思った。 kanojo ni wa sō suru riyū ga nakatta to watashi wa omotta. She had, I thought, no reason to do what she did.
	父が医者だからといって僕も医者にならなければならぬ理由はない。 chichi ga isha da kara to itte boku mo isha ni nara nakere ba nara nu riyū wa nai. There's no reason why I should become a physician because my father is one.
	兄弟とも「妻と飛行機の両方は養えない」との理由で、生涯独身を通した。 kyōdai tomo ' tsuma to hikōki no ryōhō wa yashinae nai ' to no riyū de, shōgai dokushin o tōshi ta. Saying they could not support both a wife and an airplane, the two brothers therefore spent their lives as bachelors. \| Because they "could not both support wife and airplane" the two brothers spent their lives as bachelors. \| Both brothers said that they couldn't support both a wife and an airplane, so they spent their lives as bachelors. \| The reason both brothers gave for remaining bachelors was that they couldn't support both airplanes and a wife.
	どんな理由があろうと、せっかく軌道に乗せた貿易を失墜させたのは大失態だ。 donna riyū ga aro u to, sekkaku kidō ni nose ta bōeki o shittsui sa se ta no wa dai shittai da. Whatever the reason, forfeiting the trade that we finally got on track is a fiasco.

	Examples sourced from tatoeba.org