laches

lach·es   (lāch'ĭz)    n.  A legal doctrine that bars a claimant from receiving relief where the claimant's delay in pursuing the claim has operated to the prejudice of the opposing party. [Middle English, slackness, negligence, from Anglo-Norman lachesse, laches, from Old French laschesse, from lasche, loose, remiss; see lush1.]

Main Entry: la·ches
Pronunciation: 'la-ch&z, 'lA-, -sh&z
Function: noun
Inflected Form: plural laches
Etymology: Anglo-French lachesce laschesce 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) laches> b : an affirmative defense based on this doctrine