理由(りゆう)

りゆう
noun
reason, cause
1. reason, cause, grounds
The explanation or justification for something; why something happened or is done.
理由(りゆう)は分(わ)かりません。
I don't know the reason.
遅刻(ちこく)した理由(りゆう)を教(おし)えてください。
Please tell me the reason you were late.
どんな理由(りゆう)があっても、嘘(うそ)はいけません。
No matter what the reason, lying is wrong.

理由(りゆう) is a straightforward, somewhat formal noun meaning "reason" or "grounds." It is used when explicitly stating or asking about the reason for something.

COMMON PATTERNS:

  • ～の理由(りゆう): the reason for ~
  • 理由(りゆう)を聞(き)く: to ask for a reason
  • 理由(りゆう)を述(の)べる: to state a reason
  • 理由(りゆう)なく: without reason
  • 理由(りゆう)があって: for a reason

SIMILAR WORDS:

  • 理由(りゆう): reason, justification (formal, explicit)
  • わけ: reason (conversational, often in grammatical patterns)
  • 原因(げんいん): cause (objective, scientific/technical)
  • 動機(どうき): motive (for actions, especially crimes)

REGISTER:
Appropriate for both spoken and written Japanese. More formal than わけ and commonly used in business, academic, and official contexts.

general
Added 2026.1.7 21:54 · Revised 2026.3.5 21:46
01000/01102_riyuu