Question

a shot in the dark - We could try looking in the phone book, but it will be no more than a shot in the dark.  - (Guessing a computer password) I know it's a shot in the dark, but try his mother's middle name..

Accepted Answer

a guess; an attempt to achieve something with little chance of success If you try to shoot an animal in the dark, you are not likely to hit it.

Idiom	a shot in the dark
Definition	a guess; an attempt to achieve something with little chance of success
Examples	- We could try looking in the phone book, but it will be no more than a shot in the dark. - (Guessing a computer password) I know it's a shot in the dark, but try his mother's middle name..
Note	If you try to shoot an animal in the dark, you are not likely to hit it.

Shot Dark Guess Attempt Achieve Chance Success Phone