A chemotherapy regimen consisting of mechlorethamine, vincristine (Oncovin), procarbazine and prednisone, used alone or in combination with radiation therapy for the treatment of stage I-IV Hodgkin lymphoma. Due to the increased risk of gonadal toxicity, this regimen has been widely replaced by the ABVD regimen. or An abbreviation for a chemotherapy combination used alone or with radiation therapy to treat Hodgkin lymphoma. It includes the drugs mechlorethamine hydrochloride, vincristine sulfate (Oncovin), procarbazine hydrochloride, and prednisone. Also called MOPP.