Humongous is the standard spelling of the adjective meaning extraordinarily large. The exact origins of the word are mysterious, but the earliest instances of humongous in print are found in American publications from the early 1960s. The word is probably a fusion of huge, monstrous, and tremendous. Some dictionaries list humungous as an alternative spelling, but humongous has taken root in the language and is now far more common than the alternative.
Humongous might be considered out of place in formal writing because it is still a new word. Huge, large, colossal, immense, and enormous are potential replacements. On the spectrum of formality, humongous may be less serious than those synonyms, but it’s more formal than ginormous, an even newer coinage formed by fusing giant and enormous.
Pronunciation varies. Some people pronounce it according to the alternative spelling (hue-MUNG-us), and some pronounce it according to the conventional spelling (hue-MONG-us).
But then he crossed his arms behind his head, and – bam! – out popped humongous biceps, like mountains on the horizon of his humeri. [Globe and Mail]
A single giant molecular cloud containing a million solar masses does not contract to form a single humongous star. [Universe: Solar System, Stars, and Galaxies]
It has tee boxes pushed up against the fences of the property, and a large golf course has grown simply humongous. [Washington Post]
The menu includes all the typical diner options: blue-plate specials, chicken potpie, salads, humongous desserts, and all-day breakfast. [Frommer’s San Francisco With Kids]
If you include overseas Chinese consumption of luxury products, it’s humongous. [Forbes]