Source : Webster's Revised Unabridged Dictionary (1913)

Emesis \Em"e*sis\, n. [NL., fr. Gr. ?. See {Emetic}.] (Med.)
   A vomiting.

Source : WordNet®

emesis
     n : the reflex act of ejecting the contents of the stomach
         through the mouth [syn: {vomit}, {vomiting}, {regurgitation},
          {disgorgement}, {puking}]