In [[Roman mythology]], '''Sancus''' was the [[god]] of loyalty, honesty, and oaths. His [[cult]] is one of the most ancient of Romans, probably derived from [[Etruscan mythology|Etruscan]] or [[Oscan]] influences.
He was also the god who protected loyalty in [[commerce]], and [[contract]]s in particular. Some forms of swearings were used in his name and honour at the moment of the signing of contracts and other important civil acts. Some words (like [[sanction]] - for the case of disrespect of pacts) have their etymology in the name of this god, whose name is connected with ''sancire'' "to hallow" (hence ''sanctus'', "hallowed").
There was a temple to him on the [[Quirinale]] Hill, under the name Semo Sancus Dius Fidus.
