Is it farther or further?
1550s, "favored food or drink of the gods," from Latin ambrosia, from Greek ambrosia "food of the gods," fem. of ambrosios, probably literally "of the immortals," from a- "not" (see a- (3)) + mbrotos, related to mortos "mortal," from PIE *mer- "to die" (see mortal (adj.)). Applied to certain herbs by Pliny and Dioscorides; used of various foods for mortals since 1680s (originally of fruit drinks); used figuratively for "anything delightful" by 1731.
The food of the gods in classical mythology. Those who ate it became immortal.
Note: Particularly delicious food is sometimes called “ambrosia.”