Yeah, marked by dignity or grandeur. The month August gets its name from Augustus Caesar, august the adjective comes from the Latin augustus/augur. I'm guessing that word came into play during or after Augustus' reign as a nod to the great Emperor saying something was great or grand (as the emperor had been). Or Augustus was named such with great/grand being the meaning behind his name. I don't really feel like looking into the dates and stuff right now, but yeah.