Green’s Dictionary of Slang

a hypothetical and enormous number, a multiple of many millions; thus squillionaire n., an enormously rich person, also attrib.

1878		Dean Lippicott’s Magazine of Popular Lit. & Science Mar. 379: ‘Betcher million, billion, squillion dollars ’tain’t’.
1898		Twenty-First Annual Report of the Iowa State Dairy Assoc. (Des Moines, IL) 46: The loss consequent on the foregoing conditions cannot be [...] approximately estimated, and we may as well adopt the language of the small boy, when he is betting heavily—‘a thousand, hundred, billion, million, squillion’.
1901		N.Y. Tribune 7 July 38/3: Dey say ’tis so many billions an’ squillions o’ miles from hyar to de sun .
1915		Ocala Eve. Star (FL) 19 Apr. 2/3: Squillions of young fish in the water from Silver Springs to the sea.
1922		Hutchinson News (KS) 25 Sept. 10/5: [advert] A Million Dollar Smile — a ‘squillion’ dollar’s worth of clothes.
1943		Z.N. Hurston in Amer. Mercury LVII 456/2: The deep blue sea [...] was a pearly blue, like ten squillion big pearl jewels dissolved in running gold .
1944		D. Runyon Runyon à la Carte 117: I am enjoying a privilege that any actor will give a squillion dollars to experience.
1952		Cincinnati Enquirer (OH) 24 July 5/1: Squillionaire T. Manville’s new sister-in-law.
1954		News Review (Roseburg, OR) 6 Nov. 4/4: It is proposed [...] to spend a squillion dollars on this or that.
1963		Hobbs Dly News-Sun (NM) 23 June 9/1: About a squillion frogs [...] were giving a concert.
1974		Jrnl & Courier (Lafayette. IN) 11 Feb. B4/2: Sandy hasn’t rescued her. Nor have Daddy Warbucks’s squillions.
1981		S. McAughtry Belfast 44: In the inky darkness of outer space a warhead [...] hurtles it at two squillion miles an hour.
1992		K. Lette Llama Parlour 91: It’ll help with C.J. I owe him squillions.
1999		Guardian G2 29 Sept. 16: The squinting squillionaire’s response was textbook Freudian.
2000		Indep. Rev. 7 Jan. 17: A squillion other films you could mention.
2000		Indep. Rev. 4 Apr. 7: One squillionaire rock star.
2003		Democrat & Chron. (Rochester, NY) 16 July 8F/5: S squillion years ago a UFO landed here.
2007		(ref. to 1911) Chicago Trib. section 5 25 Dec. 10/2: Noel Coward wrote letters with effusive glee. As a 12-year-old he would send home ‘squillions of kisses’.
2014		Santa maria (CA) 28 July D6/2: Handing over squillions for Suarez now would make them complicit.