Green’s Dictionary of Slang

(US) without a doubt, irrefutably.

1914		Syracuse Herald 27 Mar. 8/3: ‘Postolutely you’re right!’ Gus declared, also giving Mr. Blodger a scornful glance. ‘As long as he loses his money I’ll shake dice with him, but socially I wouldn’t have anything to do with him. Absotively and postolutely not!’.
1926		Wood & Goddard Dict. Amer. Sl.
1928		O.R. Cohen Florian Slappey Goes Abroad 126: I ain’t gwine stan’ it. I absotively ain’t.
1938		Braun & Blake Nutt Family 67: Ah am absotively sound an’ sane if anybody ever wuz.
1946		St. Cloud Times (MN) 17 Dec. 14/4: It seems only yesterday that ‘flappers’ and ‘vamps’ rolled their stockings, danced the Charleston, and used expressions like ‘absotively’ and ‘banana oil!’.
1953		S. Harris Father Divine, Holy Husband 52: For slightly larger fees, they sold numbers ‘absotively posilutely’ guaranteed to win on the next day’s policy wheel.
1968		B. Dryer Torch Bearers 148: The most posolutely absotively gorgeous hunk .
1970		O.R. Cohen Bigger and Blacker 85: I is sad; absotively mis’able.
1970		G. Sorrentino Aberration of Starlight 113: When we play croquet even he won’t talk unless he absotively has to.
1984		Clifton Clarion (AZ) 19 June R6/1: No, no, a thousand times no. It is absotively and posituitely none of these!
1999		W. Percy Lancelot 195: ‘Is he really going to buy me a piano?’ ‘Absotively.’.
2005		N. Gaiman Anansi Boys 178: ‘You’re offering me four and a half million pounds? In cash?’ [...] ‘Absatively.’.
2006		ebay 29 Jan. 🌐 I have this dictionary of American slang [...] and of course this book (which was published in 1994) is absotively dated as we continue to flay the English language on a daily basis.