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