air bag

noun

1. an inflatable plastic bag mounted under the dashboard or on the back of the front seat of a car: it cushions the driver and passengers by inflating automatically in the event of collision.

noun

1. a safety device in a car, consisting of a bag that inflates automatically in an accident and prevents the passengers from being thrown forwards
2. one of a number of large inflatable bags comprising part of a spacecraft’s landing system, enabling the craft to come to rest through a series of bounces