"blooming, being in flower; apt to effloresce," 1741, from Latin efflorescentem (nominative efflorescens), present participle of efflorescere "to bloom, flourish," from assimilated form of ex "out" (see ex-) + florescere "to blossom," from flos "flower" (from PIE root *bhel- (3) "to thrive, bloom").
