1919, Peter Clark MacFarlane, The Exploits of Bilge and Ma, Boston: Little, Brown, & Company, →LCCN, →OL, page 108:
Curfew absitively must not ring!
1919, George Allen England, Keep Off the Grass, Boston: Small, Maynard & Company, →LCCN, →OL, ch. VII, page 94:
His heart being weak, of course they couldn't draft him, but anyhow they just absitively insisted on his going to work.
1973 March 11, “Major Fred C. Dobbs”, in M*A*S*H[1], season 1, episode 22:
"Colonel Blake has okayed my transfer." "You're serious, Frank. You're leaving." "Absitively." "Gee, Frank, this place won't seem the same without you. It'll be terrific."