1.
reason, cause, grounds
The explanation or justification for something; why something happened or is done.
理由 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: the reason for ~
- 理由を聞く: to ask for a reason
- 理由を述べる: to state a reason
- 理由なく: without reason
- 理由があって: for a reason
SIMILAR WORDS:
- 理由: reason, justification (formal, explicit)
- わけ: reason (conversational, often in grammatical patterns)
- 原因: cause (objective, scientific/technical)
- 動機: 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.