Source : Webster's Revised Unabridged Dictionary (1913)

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.