1674, "showy brilliance," from Fr.
éclat "splinter, fragment" (12c.), also "flash of brilliance," from
eclater "burst out, splinter," from O.Fr.
esclater, of uncertain origin, perhaps from a W.Gmc. word related to
slit or to O.H.G.
sleizen "tear to pieces; to split, cleave." Extended sense of "conspicuous success" is first recorded in Eng. in 1741.