exuberant (adj.)

mid-15c., "over-abundant," from Latin exuberantem (nominative exuberans) "superfluous; extraordinary," present participle of exuberare "be abundant, grow luxuriously," from ex, here probably "thoroughly" (see ex-), + uberare "be fruitful," related to uber "udder," from PIE root *eue-dh-r- (see udder). From 1510s as "growing luxuriantly;" figurative use, of affections, joyous emotions, etc., is by 1640s. Related: Exuberantly; exuberate; exuberating.