Is it ensure, insure, or assure?
c.1300, glideren (late 14c. as gliteren), from a Scandinavian source, cf. Old Norse glitra "to glitter," from glit "brightness," from Proto-Germanic *glit- "shining, bright" (cf. Old English glitenian "to glitter, shine; be distinguished," Old High German glizzan, German glitzern, Gothic glitmunjan), from PIE *ghleid- (cf. Greek khlidon, khlidos "ornament"), from root *ghel- "to shine, glitter" (see glass). Related: Glittered; glittering. The noun is c.1600, from the verb. Glitter rock is from 1972.
A gaudy style of dress and grooming affected by some musicians, comprising dyed hair, jewels on face and body, and refulgent jumpsuits and cowboy suits (1960s+)