"action of restraining; means of restraint," early 15c., from Old French restreinte, noun use of fem. past participle of restraindre (see restrain). Sense of "reserve" is from c. 1600.
the unlawful restraint of trade
he was a model of polite restraint
dogs should be kept under restraint
restraints imposed on imports
the room was simply decorated with great restraint
the car did not have proper restraints fitted