Green’s Dictionary of Slang

(orig. US) enormous, outsized, huge.

1967		Cosmos (Coe College, Iowa) 5 May 2/4: Maybe at the bottom there will be something worthwhile that us humble sheep, your poor blind, flock, will gather around that humongous soapbox in the sky to listen to.
1967		Current Sl. II:2 18: Humangous, adj. One size larger than manjonious.
1970		Wash. Post 21 Aug. D7/5: [classified advert] Used boats -- humongeous savings on all remaining models!
1976		New Yorker 16 Aug. 26: She uses expressions like ‘the whole megillah’ (meaning the whole long story) and ‘humongous’ (meaning huger than huge and more tremendous than tremendous).
1983		Totally True Diaries of an Eighties Roller Queen 🌐 14 Aug. I’m going to the recreation center right next door to the high school. It has a whirlpool, humungus pool, six diving boards [...] and an ice rink that’s open in the summer.
1989		C. Hiaasen Skin Tight 256: Not humongous titties but nice pointy ones.
1993		M. Myers et al. Wayne’s World II [film script] garth: My dad would start off with a humungoid bowl of Hormel’s extra spicy chili.
1998		Source Oct. 176: Alongside the humongous and windowless maquila factories.
2000		Guardian G2 7 Mar. 13: It’s this humongous fishing trip.
2004		P. Howard PS, I Scored the Bridesmaids 79: He sees the humungous stack of Valeys on my bed.
2004		Mad mag. Nov. 60: How come you drive such a humogous [sic] gas-guzzling SUV?
2010		C. Hiaasen Star Island (2011) 33: Maury Lykes had invested a humongous sum of money.
2012		J. Fagan Panopticon (2013) 255: A humongous spliff clamped in her gob.
2020		C. Hiaasen Squeeze Me 54: How often does a person get the chance to see a humongous headless serpent?
2021		P Howard Braywatch 233: [A] humungous Montecristo burning between his fingers.