c. 1200, from a Scandinavian source akin to Old Norse þrifask "to thrive," originally "grasp to oneself," probably reflexive of þrifa "to clutch, grasp, grip, take hold of" (compare Norwegian triva "to seize," Swedish trifvas, Danish trives "to thrive, flourish"), of unknown origin. Related: Thrived (or throve); thriving.
