1660s, from L. augustus "venerable," probably originally "consecrated by the augurs, with favorable auguries" (see augur); or else "that which is increased" (see augment).
"eighth month," 1097, from L. Augustus, sixth month of the Roman calendar, named for emperor Augustus Cęsar, lit. "Venerable Cęsar" (see august). Replaced native Weodmonaš "weed month."