August: [OE] The month of August was named by the Romans after their emperor Augustus (63 BC–14 AD). His name was Caius Julius Caesar Octavian, but the Senate granted him the honorary title Augustus in 27 BC. This connoted ‘imperial majesty’, and was a specific use of the adjective augustus ‘magnificent, majestic’ (source of English august [17]); it may derive ultimately from the verb augēre ‘increase’ (from which English gets auction and augment). => auction, augment
august (adj.)
1660s, from Latin augustus "venerable, majestic, magnificent, noble," probably originally "consecrated by the augurs, with favorable auguries" (see augur (n.)); or else "that which is increased" (see augment).
August
eighth month, 1097, from Latin Augustus (mensis), sixth month of the later Roman calendar, renamed from Sextilis in 8 B.C.E. to honor emperor Augustus Caesar, literally "Venerable Caesar" (see august (adj.)). In England, the name replaced native Weodmonað "weed month."