1670s, "showy brilliance," from French éclat "splinter, fragment" (12c.), also "flash of brilliance," from eclater "burst out, splinter," from Old French esclater "smash, shatter into pieces," of uncertain origin, perhaps from a West Germanic word related to slit or to Old High German sleizen "tear to pieces; to split, cleave." Extended sense of "conspicuous success" is first recorded in English in 1741.