retch

(noun) an involuntary spasm of ineffectual vomiting. Synonyms: heave. Examples: "A bad case of the heaves."

(verb) eject the contents of the stomach through the mouth. Synonyms: vomit, vomit up, purge, cast, sick, cat, be sick, disgorge, regorge, puke, barf, spew, spue, chuck, upchuck, honk, regurgitate, throw up. Examples: "After drinking too much, the students vomited." "He purged continuously." "The patient regurgitated the food we gave him last night."

(verb) make an unsuccessful effort to vomit; strain to vomit. Synonyms: gag, heave.