antitoxin

an·ti·tox·in

noun \ˌant-i-ˈtäk-sən\

Definition of ANTITOXIN

: an antibody that is capable of neutralizing the specific toxin (as a specific causative agent of disease) that stimulated its production in the body and is produced in animals for medical purposes by injection of a toxin or toxoid with the resulting serum being used to counteract the toxin in other individuals; also : an antiserum containing antitoxins