term:

Laches

laches n

pl: laches
[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) [a suit barred by ]
b : an affirmative defense based on this doctrine

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.