mega

Etymology

From the prefix mega-, from Ancient Greek μέγας (mégas, “great, large, mighty”).

adj

1. (informal) Very large.
   Follow those in the know to the fifth floor of Sega's Joy Polis, a mega indoor amusement park that's part of the Odaiba Decks Tokyo Bay entertainment complex near Tange's Fuji Television building. 2004, Nigel Coates, Collidoscope: new interior design, page 26
2. (slang) Great; excellent.
   We had a mega time until Peter fell in the fish pond and cut his leg. 1998, John Barwick, Targeting Text, page 25
   It was totally mega. The audience clapped and cheered when Teasel had finally finished. So did I. 2011, Anna Wilson, Pup Idol: Top of the Pups
   July 15, 2011, Liam Gallagher, quoted at the launch of the new Manchester City F.C. kit I've been a City fan since I was a kid, so to be involved with the launch of a new kit is colossal. Manchester City fans are known for having a lot of style and the new shirt looks mega.

adv

1. (informal) extremely
   mega-fun; mega rich

noun

1. (mathematics) The Steinhaus-Moser number ②