What roundcat said, pretty much.
People sometimes also talk about "live outs", which are the outs you have that are still available in the deck.
If you get all in with the abovementioned QJ vs AK, you've got six live outs - three quees and three jacks (assuming your opponent doesn't improve). If someone (as someone invariably does) then says
"Oh, I folded a QJ as well" then two of your outs are now "dead" because you know they can't possibly be dealt, and you only have four live outs left.
This can be a big deal in stud games, where you need to keep track of how many of your outs have been dealt to other players as up cards. If you've got four diamonds on fifth street, but six diamonds have been dealt as upcards to other players'
hands, you've only got three outs to fill your flush. If there hadn't been
any diamonds dealt to other people's hands, however, you'd have nine live outs.