Alteration (after headlong) of arseling, from Middle English *arsling, from Old English earsling (“backwards, on the back”), equivalent to arse + -ling. Cognate with Dutch aarzeling, aarzelings, German ärschling, ärschlings.
arselong (not comparable)
- (Britain dialectal) Backwards; on one's arse.
1981, John Barth, Giles goat-boy:
- Heave they did, all unopposed, and tumbled arselong when the bar came about. Even as they rolled and cursed, the whistling petered; [...]