laches

noun (used with a singular verb) Law.

1. failure to do something at the proper time, especially such delay as will bar a party from bringing a legal proceeding.

noun

1. law negligence or unreasonable delay in pursuing a legal remedy

n.“negligence in performance of legal dute,” 1570s, earlier simply “slackness, negligence, want of zeal,” late 14c., from Anglo-French laches, Old French lachesse, from Old French lasche (Modern French lâche), verbal adj. from lascher, from Vulgar Latin *lascare, classical laxare, from laxus (see loose). Cf. riches.