1.
cause, origin, source
The reason why something happens or exists.
原因 means cause or origin - the reason why something happened.
COMMON PATTERNS:
- ~の原因: the cause of ~
- 原因を調べる: to investigate the cause
- 原因が分かる: to find out the cause
- 原因は~だ: the cause is ~
COMMON COLLOCATIONS:
- 事故の原因: cause of an accident
- 病気の原因: cause of illness
- 火事の原因: cause of a fire
- 問題の原因: cause of the problem
RELATED WORDS:
- 結果: result, outcome (opposite)
- 理由: reason (more personal/intentional)
- 要因: factor, contributing cause