Not a thing
Jack-all means nothing at all, typically in expressions of ignorance or worthlessness: He doesn't know jack-all about cars.
The phrase is a euphemistic variation of jack shit, softened for contexts where profanity feels inappropriate.
Both expressions use jack to mean nothing, though jack-all sounds slightly more polite.
IDEA.org / Words / jack-all
Not a thing
Jack-all means nothing at all, typically in expressions of ignorance or worthlessness: He doesn't know jack-all about cars.
The phrase is a euphemistic variation of jack shit, softened for contexts where profanity feels inappropriate.
Both expressions use jack to mean nothing, though jack-all sounds slightly more polite.
1. nothing — zilch, Informal term for naught; nada (Borrowed zero); zip (Toothed sliding fastener); nil (Nothing whatsoever); squat · diddly-squat · bupkis · goose egg · naught · nought · zippo · nix · nowt · zero
quantity/amountjack-all ≠ everything The complete set; all · the whole lot · tons · loads · a great deal
jack, all
Word data: Linguabase (CC0) · www.idea.org/words/jack-all