late 14c., from Old French lamentacion and directly from Latin lamentationem (nominative lamentatio) "wailing, moaning, weeping," noun of action from past participle stem of lamentari "to wail, moan, weep, lament," from lamentum "a wailing," from PIE root *la- "to shout, cry," probably ultimately imitative. Replaced Old English cwiþan.