The Libyan Jupiter; so called from the Greek ammos
(sand), because his temple was in the desert. Herodotus calls it an
Egyptian word (ii. 42).
Son of Jupiter Ammon.
Alexander the Great. His father, Philip, claimed to be a descendant
of Hercules, and therefore of Jupiter; and the son was saluted by the
priests of the Libyan temple as son of Ammon. Hence was he called the
son or descendant both of Jupiter and of Ammon.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894