From the prefix mega-, from Ancient Greek μέγας (mégas, “great, large, mighty”).
Meanings
(informal, not-comparable) 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:
(not-comparable, slang) Great; excellent.
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:
We had a mega time until Peter fell in the fish pond and cut his leg. 1998, John Barwick, Targeting Text, page 25:
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.
fi mahtava (great, excellent) · fi mega- (very large) · el μέγας (great, excellent) · fi erinomainen (great, excellent) · fi jättiläis- (very large) · el μέγας (very large)
From the prefix mega-, from Ancient Greek μέγας (mégas, “great, large, mighty”).
Meanings
(informal) A megararity (extremely rare bird for a certain region).
And, speaking of relative banalities, the recurring Semipalmated Plover at the Broom Sewage Works may have inured us slightly to the status of the species as a rare vagrant, but it was an undeniable "mega" when one was discovered on Lord Howe Island on 23 March. 2017 June 14, Australian Birdlife, Carlton, Victoria, page 76, column 2: