ambrosia (n.)

1560s, "favored food or drink of the gods," from Latin ambrosia, from Greek ambrosia "food of the gods," noun use of fem. of ambrosios, probably literally "of the immortals," from ambrotos "immortal, imperishable," from a- "not" (see a- (3)) + mbrotos, related to mortos "mortal," from PIE root *mer- "to rub away, harm" (also "to die" and forming words referring to death and to beings subject to death). 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.