Green’s Dictionary of Slang

(orig. US) an unspecified, very large number.

1916		Oakland Trib. (CA) 12 Dec. 6: They’re going to bring ’em over here—zillions of ’em.
1919		A. Baer Flapping Over New Leaves 4 Jan. [synd. col.] He turned over about eleven billion gazillion dollars.
1921		Chicago Defender 4 June 7: He has a smile that’s worth a ‘zillion dollars’ and a ‘bay window’ as large as Old Roll Top’s and Whit Viney’s put together.
1934		H. Roth Call It Sleep (1977) 269: Mor’n’ a zillion rubbuh ben’s he had on id.
1944		D. Runyon Runyon à la Carte 23: How anybody can be lonely with all his zillions is a great mystery to me.
1957		F. Kohner Gidget (2001) 11: I’m suffering from an inferiority complex on account of my old man having zillions of books around the house.
1962		Mad mag. Dec. 24: A billion, skillion, zillion dollars.
1978		P. Theroux Picture Palace 306: I’d do the ultimate panning shot, around the world in a zillion frames.
1982		P. Redmond Tucker and Co 106: He trudged off to detention for the zillionth time.
1983		J. Byrell (con. 1959) Up the Cross 116: Lady Cynthia [...] gave him her zillion dollar smile.
1987		G. Tate ‘Michael Jackson’ in Flyboy in the Buttermilk (1992) 97: Never mind how many of those kerzillion LPs we bought.
1991		Isaac Asmiov’s Science Fiction Mag. Jan. 14/1: One hundred thousand factorial is not "ten to the godzillionth power", but rather the much more modest ten to the 45673.450899970908360663394094748 (approximately).
1993		J. Mowry Six Out Seven (1994) 22: Opening the window for air brought in b’zillions of flies.
1996		J. Byrell Lairs, Urgers & Coat-Tuggers 255: [O]ne of the zillion occasions he looked like getting the heave-ho from his Darlo boarding house.
1996		S. Frank Get Shorty [film script] escobar: Now why would you do that? Put the money in a locker? bo catlett: Because there were a zillion DEA guys hanging around the terminal escobar: (flat) A zillion, huh? That’s a lot.
2001		Guardian G2 31 May 7: It is a gajillion miles away.
2002		Fabian & Byrne Out of Time (ms.) 42: Behind the desk this whey-faced fuzz was staring at me as though I was the dregs of society. We were probably the same age but a zillion years apart.
2015		J. Stahl OG Dad 6: My viral load [...] ‘looked like something out of Ray Bradbury. Way up there in the bazillions’ [...] After one week on a cocktail of AIDS-drug adjacent protase inhibitors [...] my count went down from a quarter of a gazillion to twenty-three.
2015		L. McInerney Glorious Heresies 7: [A] million zillion years from morphing into a horny stripper.
2017		Observer 25 June 15/1: I have some sympathy for multi-kazillionaire feudal landowners William and Harry. They didn’t ask to be princes.
2019		S.M. Jones Lives Laid Away [ebook] ‘Interference from the bazillion satellites junking it up out there’.
2023		J. Jackson Pineapple Street 144: [A] zillion things to do that were more fun that [sic] watching the kids ride their bikes in circles for hours.