1274, from O.Fr. faon "young animal," from V.L. *fetonem, acc. of *feto, from L. fetus "an offspring" (see fetus). Still used of the young of any animal in King James I's private translation of the Psalms, but mainly of deer from 15c. Color use is 1881.
O.E. fagnian "rejoice," from fægen "glad" (see fain); used in M.E. to refer to expressions of delight, especially a dog wagging its tail, hence "act slavishly" (early 14c.). Related: Fawned; fawning.