Making a hand with the last two cards dealt, and may end up not being a hand originally intended to make.
For example, if you have 3 cards to a flush and get both the cards you need, it is said you’ve made a “backdoor flush draw”. It’s not often you’ll hear players say that they hit a “runner-runner” flush.
EXAMPLE “It is good to consider backdoor outs when you’re thinking about bluffing.”