Why is the ninth month called September?
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.”