Note that parenthetical contradicts the "zero days to fix" definition. (No patch available is not zero days to fix "in other words".) That suggests the term as

Note that parenthetical contradicts the "zero days to fix" definition. (No patch available is not zero days to fix "in other words".) That suggests the term as commonly understood is a bit fuzzy. Personally, I've noticed more use of "zero-day" to mean "exploits are now public but no patch is yet available" than to mean literally "programmers just learned of the bug today".