august (adj.) Look up august at Dictionary.com
"inspiring reverence and admiration, solemnly grand," 1660s, from Latin augustus "venerable, majestic, magnificent, noble," perhaps originally "consecrated by the augurs, with favorable auguries" (see augur (n.)); or else [de Vaan] "that which is increased" (see augment).
August Look up August at Dictionary.com
eighth month, late 11c., from Latin Augustus (mensis), sixth month of the later Roman calendar, renamed from Sextilis (literally "sixth") in 8 B.C.E. to honor emperor Augustus Caesar, literally "Venerable Caesar" (see august (adj.), and compare Augustus). One of two months given new names to honor Roman leaders (July being the other), the Romans also gave new imperial names to September (Germanicus) and October (Domitian) but these did not stick.

In England, the name replaced native Weodmonað "weed month." Traditionally the first month of autumn in Great Britain, the last of summer in the U.S.