約定俗成 yuē dìng sú chéng

DEFINITIONS

  1. established by popular usage (idiom); common usage agreement
  2. customary convention

CHARACTERS

約 yuē treaty, agreement, covenant
定 dìng
HSK 3
decide, settle, fix
俗 sú
HSK 5
social customs; vulgar, unrefined
成 chéng
HSK 3
completed, finished, fixed