Definition - Noun [Anglo-French lachescelaschesce negligence, from Old French lasche lax, ultimately from Latin laxare to loosen, from laxus slack] 1: undue delay in asserting a right or privilege compare statute of limitations 2 a: a doctrine permitting dismissal of a suit because a plaintiff's unreasonable delay in asserting a right or privilege has been detrimental to the defendant's ability to make a defense (as by resulting in the unavailability of witnesses or evidence) <a suit barred by ~> b: an affirmative defense based on this doctrine Pronunciation'la-ch&z, 'lA-, -sh&z