1. a substance (a virus or toxin or immune serum) that is introduced into the body to produce or increase immunity to a particular disease; [syn: inoculant, inoculum]
WordNet (r) 3.0 (2006):
inoculant
n 1: a substance (a virus or toxin or immune serum) that is
introduced into the body to produce or increase immunity to
a particular disease [syn: inoculant, inoculum]