restraint
/ri-ˈstrānt/
noun
an act of restraining : the state of being restrained
a means of restraining : a restraining force or influence
a device that restricts movement
noun
a resilient pad at the top of the back of an automobile seat especially for preventing whiplash
noun
a restraint (such as a self-locking seat belt) that acts automatically to protect an automobile rider during a crash