-in

Tetrazine Tet*raz"ine, n. Also -in -in . [Tetrazo- + -ine.] (Chem.) A hypothetical compound, {C2H2N4} which may be regarded as benzene with four {CH} groups replaced by nitrogen atoms; also, any of various derivatives of the same. There are three isomeric varieties. [Webster 1913 Suppl.]