Source : Webster's Revised Unabridged Dictionary (1913)

Tetrazole \Tet*raz"ole\, n. [Tetrazo- + -ole.] (Org. Chem.)
   A crystalline acid substance, {CH2N4}, which may be regarded
   as pyrrol in which nitrogen atoms replace three {CH} groups;
   also, any of various derivatives of the same.