The Collaborative International Dictionary of English v.0.48:

Emetic \E*met"ic\, a. [L. emeticus, Gr. ?, fr. ? to vomit, akin
   to L. vomere: cf. F. ['e]m['e]tique. See Vomit.] (Med.)
   Inducing to vomit; exciting the stomach to discharge its
   contents by the mouth. -- n. A medicine which causes
   vomiting.
   [1913 Webster]

WordNet (r) 3.0 (2006):

emetic
    n 1: a medicine that induces nausea and vomiting [syn: emetic,
         vomit, vomitive, nauseant]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "emetic":
   abstergent, cathartic, cleaner, cleaning, cleaning agent,
   cleaning solvent, cleanser, cleansing, cleansing cream, cold cream,
   cream, dentifrice, depurant, depurative, detergent, disgustingness,
   diuretic, enema, expurgatory, fetidness, foulness, holystone,
   loathsomeness, lotion, lustral, mouthwash, nastiness, nauseant,
   nauseousness, obnoxiousness, odiousness, offensiveness,
   overripeness, pumice stone, purgative, purge, purging,
   purificatory, purifier, purifying, rancidity, rancidness, rankness,
   repugnance, repulsiveness, rinse, rottenness, shampoo, sickener,
   soap, solvent, synthetic detergent, tooth powder, toothpaste,
   vileness, vomit, vomitive, vomitory, wash