1) Antigen 2) Bacterial toxin 3) Toxoid 1) Toxoid 
Synonym for toxoid ... <pharmacology> Nontoxic derivative of a bacterial exotoxin produced by formaldehyde or other chemical treatment: useful as a vaccine because it retains most antigenic properties of the toxin. ... (12 Jan 1998) ... 
Type: Term Pronunciation: an′ă-tok′sin Synonyms: toxoid
[n] - a bacterial toxin that has been weakened until it is no longer toxic but is strong enough to induce the formation of antibodies and immunity to the specific disease caused by the toxin
toxoid noun a bacterial toxin that has been weakened until it is no longer toxic but is strong enough to induce the formation of antibodies and immunity to the specific disease caused by the toxin; `diphtheria toxoid`