According to Egyptian Mythology, Khonsu (Chons), was the third member (with his parents Amen and Mut) of the great triad of Thebes. He was the god of the moon. The best-known story about him tells of him playing the ancient game "senet" ("passage") against Thoth, and wagered a portion of his light. Thoth won, and because of losing some of his light, Khonsu cannot show his whole glory for the entire month, but must wax and wane.
SEE ALSO Amen, Mut, Toth.
[Source: Shawn C. Knight, "Egyptian Mythology FAQ" ]