superantigen

su·per·an·ti·gen

noun \-ˈant-i-jən\

Definition of SUPERANTIGEN

: a substance (as an enterotoxin) that acts as an antigen capable of stimulating much larger numbers of T cells than an ordinary antigen

—su·per·an·ti·gen·ic \-ˌant-i-ˈjen-ik\ adjective