The Collaborative International Dictionary of English v.0.48:

anthelminthic \anthelminthic\, Anthelmintic
\An`thel*min"tic\([a^]n`th[e^]l*m[i^]n"t[i^]k), a. [Pref. anti-
   + Gr. "e`lmins, -inqos, worm, esp. a tapeworm, or mawworm.
   See also helminth] (Med.)
   capable of expelling or destroying parasitic worms. -- n. An
   anthelmintic remedy. [Written also anthelminthic.]

   Syn: helminthic, parasiticidal
        [1913 Webster WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

anthelmintic
    adj 1: capable of expelling or destroying parasitic worms [syn:
           anthelmintic, anthelminthic, helminthic,
           parasiticidal]
    n 1: a medication capable of causing the evacuation of parasitic
         intestinal worms [syn: vermifuge, anthelmintic,
         anthelminthic, helminthic]