What is "tetrazole"

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.

n. (context organic compound English) A five-membered heterocycle having one carbon atom, four nitrogen atoms and two double bonds

Tetrazoles are a class of synthetic organic heterocyclic compound, consisting of a 5-member ring of four nitrogen and one carbon atom (plus hydrogens). The simplest is tetrazole itself, CHN. They are unknown in nature.