Something auspicious augurs well; it favors or is conducive to success. The oldest known use of the adjective is credited to Shakespeare, but its history dates back to the ancient Romans.

The Romans believed it was possible to detect omens of good and evil in the flying patterns and feeding practices of birds. The seer granted the ability to interpret such omens was originally known as an auspex (after avis, Latin for "bird," plus specere meaning "to look at"); over time, auspice came to refer to "a prophetic sign."

Supposedly, only a chief commander was permitted to divine the auspices of war, so when a Roman subordinate was responsible for a victory, he was said to have won the battle "under the auspices of his leader." True or not, we do know that the plural auspices developed the sense "patronage and kindly guidance; protection."