Main Entry: an·ti·gen

Pronunciation: \ˈant-i-jən\

Function: noun

: any substance (as an immunogen or a hapten) foreign to the body that evokes an immune response either alone or after forming a complex with a larger molecule (as a protein) and that is capable of binding with a product (as an antibody or T cell) of the immune response

[antigen illustration]

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

—an·ti·gen·i·cal·ly \-i-k(ə-)lē\ adverb