seat belt
noun [ C ] uk/ˈsiːt ˌbelt/ us/ˈsiːt ˌbelt/ (also safety belt)
（坐椅）安全带
a belt that fastens around you when you are travelling in a vehicle or aircraft and holds you in your seat, in order to reduce the risk of being injured in an accident
Please fasten/do up your seat belts. 请系上安全带。
You must wear your seat belt. 你一定要系好安全带。