What is the meaning of retch?

noun

• An involuntary spasm of ineffectual vomiting.
  • usage: "a bad case of the heaves"
  • synonyms: heave

verb

• Eject the contents of the stomach through the mouth.
  • usage: "After drinking too much, the students vomited"; "He purged continuously"; "The patient regurgitated the food we gave him last night"
  • synonyms: vomit, vomit up, purge, cast, sick, cat, be sick, disgorge, regorge, puke, barf, spew, spue, chuck, upchuck, honk, regurgitate, throw up
• Make an unsuccessful effort to vomit; strain to vomit.
  • synonyms: gag, heave