put someone out of his or her misery

put (someone or something) out of its/(one's) misery

1. To kill someone or something as a means to ending suffering. Considering the dog's extensive wounds, the vet encouraged us to put him out of his misery.
2. To quell one's curiosity. Oh, just put me out of my misery and tell me how the movie ends!
See also: misery, of, out, put
Farlex Dictionary of Idioms.

put someone out of his or her misery

1. Kill a wounded or suffering animal or person, as in When a horse breaks a leg, there is nothing to do but put it out of its misery. [Late 1700s]
2. End someone's feeling of suspense, as in Tell them who won the tournament; put them out of their misery. [c. 1920] Both usages employ put out of in the sense of "extricate" or "free from."
See also: misery, of, out, put, someone
The American Heritage® Dictionary of Idioms by Christine Ammer.
See also:
  • put (someone or something) out of its/(one's) misery
  • put out of misery
  • put some creature out of its misery
  • put somebody/something out of their/its misery
  • put someone out of their misery
  • put something out of its misery
  • have a dog's chance
  • dinner
  • bite on
  • bite on someone