1.
to be contrary to, to contradict, to go against
To be in opposition to a principle, expectation, or standard. Used with に to mark the thing being contradicted.
予想に反する結果だった。
The result was contrary to expectations.
常識に反する行動を取った。
He took action that went against common sense.
彼の意見は科学的な事実に反している。
His opinion contradicts scientific fact.
2.
to violate, to act against
To break or act contrary to a rule, law, or agreement. Common in legal and formal contexts.
法律に反する。
To violate the law.
契約に反する行為は許されない。
Acts that violate the contract are not permitted.
規則に反した場合は処分の対象になる。
If you violate the rules, you will be subject to disciplinary action.
COMMON COLLOCATIONS:
- 予想に反する (contrary to expectations)
- 法律に反する (violate the law)
- 規則に反する (violate the rules)
- 常識に反する (go against common sense)
- 意に反する (against one's will)
USAGE NOTES:
Always takes the particle に to mark what is being contradicted or violated. The pattern ～に反して is commonly used as a connective phrase meaning "contrary to ~." For example, 予想に反して (contrary to expectations). The noun form 反する is a する verb but is almost always intransitive.