noun
good custom; good morals; public decency
Often used in legal or formal contexts, especially in the phrase 公序良俗 (public order and morals). Refers to socially accepted moral standards and customs.
その契約は公序良俗に反するため無効です。
That contract is void because it violates public order and morals.
良俗を守ることは社会の安定につながる。
Upholding good customs leads to social stability.
Compound of 良 (good) and 俗 (custom, manners). The exact historical derivation is uncertain, but the term has been used in legal and ethical discourse since the Meiji era.