in card-playing, "act of trumping when a player has no cards of the suit led," by 1856, from ruff (v.) "trump when unable to follow suit" (1760), from the name of the old game of ruff (1580s), from French roffle, earlier romfle (early 15c.), from Italian ronfa, which is perhaps a corruption of trionfo "triumph" (from French; compare trump (n.1)). The old game, a predecessor of whist, was in vogue c. 1590-1630.
in law, "the person who begins a suit before a tribunal for the recovery of a claim" (opposed to defendant), c. 1400, pleintif, from Anglo-French pleintif (late 13c.), from noun use of Old French plaintif "complaining; wretched, miserable," in law, "aggrieved" (as in partie plaintif "the party bringing a suit at law"), from plainte (see plaint). Identical with plaintive at first; the form that receded into legal usage retained the older -iff spelling.
mid-14c., "debate, dispute;" late 14c., "litigation, the carrying on of a suit at court," verbal noun from plead (v.). Meaning "supplication, intercession" is from early 15c.
in cards, "trump when unable to follow suit," 1760, from the card game ruff (see ruff (n.2)). Related: Ruffed; ruffing.