lambent (adj.)

of light, flame, etc., "flowing or running over the surface," 1640s, from a figurative use of Latin lambentem (nominative lambens), present participle of lambere "to lick, lap, wash, bathe," from PIE root *lab-, indicative of smacking lips or licking (source also of Greek laptein "to sip, to lick," Old English lapian "to lick, lap up, to suck;" see lap (v.1)).