Yours, Etc.: Origins and Uses of 8 Sign-Offs
late 14c., "distress, oppression," from Old French constreinte "binding, constraint, compulsion" (Modern French contrainte), fem. noun from constreint, past participle of constreindre, from Vulgar Latin *constrinctus, from Latin constrictus (see constrain). Meaning "coercion, compulsion" is from 1530s.