airbag
noun [ C ] uk/ˈeə.bæɡ/ us/ˈer.bæɡ/
（汽车）安全气囊
a bag in a vehicle that automatically fills with air if the vehicle is involved in an accident, in order to protect the driver or a passenger from injury
In the event of a collision, the airbag stops the driver of the car from hitting his or her chest on the steering wheel. 如果发生碰撞事故，安全气囊会防止司机的胸部撞到方向盘上。