- Proper noun. (context, Greek god) : The son of Zeus and Leto (or Jupiter and Latona), and the twin brother of Artemis (or Diana). ''Oxford Dictionary of World Mythology'', Arthur Cotterell, Oxford University Press, 1986 He was the god of light, music, medicine, and poetry; ''Webster's College Dictionary'', Random House, 2001 and prophecy, dance, manly beauty, and more.
- Proper noun. A very handsome young man. .
- Proper noun. A United States space program, and the vehicles it created, used for human travel to the moon.
- Proper noun. A town in Pennsylvania, USA.
- Proper noun. A butterfly (''Parnassius apollo'', a large swallowtail with black and red spots on white wings).
- Proper noun. A male given name.
- Noun. (astronomy) An asteroid possessing an orbit that crosses the orbit of the Earth and an orbital period of over one year, with semimajor axes greater than 1 AU, and perihelion distances less than 1.017 AU.
- Noun. A very handsome young man.
- Noun. A butterfly, also known as mountain apollo (''Parnassius apollo'').