Is it ensure, insure, or assure?
Old English brysan "to crush, bruise, pound," from Proto-Germanic *brusjanan, from PIE root *bhreus- "to smash, crush" (cf. Old Irish bronnaim "I wrong, I hurt;" Breton brezel "war," Vulgar Latin brisare "to break"). Merged by 17c. with Anglo-French bruiser "to break, smash," from Old French bruisier "to break, shatter," perhaps from Gaulish *brus-, from the same PIE root. Related: Bruised; bruising.
1540s, from bruise (v.).
An injury to underlying tissues or bone in which the skin is unbroken, often characterized by ruptured blood vessels and discolorations; a contusion.