a long shot

long shot

1. A bet that has a low probability of winning. That horse is a long shot, but the bet will pay well if he wins the race.
2. Something that has a very small chance of succeeding. I know it's a long shot because of his busy schedule, but maybe I can convince him to help me with this project. Her candidacy was a long shot from the beginning, and her landslide defeat was no surprise.
See also: long, shot
Farlex Dictionary of Idioms.

a long shot

COMMON
1. If you describe a way of solving a problem as a long shot, you mean that there is little chance that it will succeed, but you think it is worth trying. You could try to find her. It's a long shot but you could start with the phone book.
2. You can also say that something is a long shot when it is very unlikely to happen. It seemed such a long shot, me walking over the hills, and seeing you at the end of it. Compare with by a long shot. Note: The reference here is to someone shooting at a target from a very long distance.
See also: long, shot
Collins COBUILD Idioms Dictionary, 3rd ed.

a ˈlong shot

(informal) an attempt or a guess which you do not expect to be successful but which is worth trying: Try ringing him at home. It’s a long shot, I know, but he might just be there. ‘Are you going to apply for the manager’s job?’ ‘I don’t know. It’s a bit of a long shot, isn’t it?’A long shot is a shot fired from a long distance and so unlikely to hit its target.
See also: long, shot
Farlex Partner Idioms Dictionary

long shot, (not by) a

(Not) a remote chance. Early firearms were notoriously inaccurate, and a shot from a distance rarely hit the target. In the late eighteenth and early nineteenth centuries a long shot meant just that, a shot fired from afar. By the late nineteenth century the term had been transferred to other improbable circumstances, such as a wild guess or, more specifically, a bet against considerable odds. From about 1865, however, it also meant far-fetched, as in this OED citation from Young Gentleman’s Magazine (1873): “This did not, however, suit her long-shot tactics.”
See also: long
The Dictionary of Clichés by Christine Ammer
See also:
  • long shot
  • long shot, (not by) a
  • long shot, a
  • bet on
  • bet on (someone or something)
  • play the field
  • play the field, to
  • bet on it
  • bet (one's) boots
  • welch on (someone or something)
References in periodicals archive
My parents weren't Communists by a long shot. My father was a New Jersey chicken farmer who made the mistake of attending a meeting to discuss the price of eggs; an FBI agent picked him up for interrogation as he walked home.
KEEPING AN EYE OUT