c.1400, from Anglo-Fr. pleintif (1278), noun use of O.Fr. plaintif "complaining," from pleint (see plaint). Identical with plaintive at first; the form that receded into legal usage retained the older -iff spelling.
Main Entry: plain·tiff Pronunciation: 'plAn-t&f Function: noun Etymology: Middle French plaintif, from plaintif, adj., grieving, from plaint lamentation, from Latin planctus, from plangere to strike, beat one's breast, lament : the party who institutes a legal action or claim (as a counterclaim) —see also COMPLAINANT, COMPLAINT, LIBELLANT —compare DEFENDANT, PROSECUTION