Green’s Dictionary of Slang

extremely large, enormous.

1942		F.A. Walbank Air force Anthology 111: If you write a book or get your name in a paper that is a ‘ginormous line,’ the strange word being evolved from gigantic and enormous.
1944		RAF Quarterly XVI–XVII 42/2: Squadron Leader Ian has a score of five for one sortie. This is a record for night-fighting and we are determined as soon as there is a lull in activity to celebrate with a ginormous party.
1958		C. Lee diary 24 June in Eight Bells and Top Masts (2001) 130: He’s given me the most ginormous list of definitions to learn.
1958		Aeronautical Journal LXII n.p.: From a similar source comes an illustration of a row of “ginormous” rockets, opposite p. 109, which recently frightened the Daily Express.
1964		J. Gardner Liquidator 129: The object of the exercise is to test their security reaction to a ginormous emergency.
1979		R. Morris HMS Colossus 113: ‘There’s a ginormous rock on top of her,’ I said. And so there was, a rock as big as a two-storeyed house.
1987		Verbatim XIV-XV 29/2: There is little point in wasting space in this review to comment at length on the huge (ginormous, humongous) expansion that the lexicon of English has undergone during the past two decades.
1990		A. Duff Once There Were Warriors 169: In the crapper — jeez! at a ginormous fart exploding out ofim. Wigglin around on the seat trying to hold the rest in, because of the embarrassment.
2006		J. Sommerfeld May Day n.p.: I picked up the picture she had just sent me of her and Rodney, each holding one end of a ginormous salmon.
2010		S. Selfors Coffeehouse Angel 140: One ginormous rat meant that there might be other ginormous rats lying in wait to conquer the world.
2022		J. Hannaham Didn’t Nobody Give a Shit 90: A ginormous supermarket.