tetrazo-

from The Collaborative International Dictionary of English v.0.48

Tetrazo- \Tet*raz"o-\, a. [Tetra- + azo-.] (Chem.)
   A combining form (also used adjectively), designating any one
   of a series of double derivatives of the azo and diazo
   compounds containing four atoms of nitrogen.
   [1913 Webster]