https://doi.org/10.1351/goldbook.D01689
Compounds having the structure $\ce{RN=N–NR2}$ (not all $\ce{R = H}$, and one $\ce{R}$ commonly aryl). In systematic nomenclature, diazoamino prefixed to the name of $\ce{RH}$ names the compound $\ce{RN=NNHR'}$ ($\ce{R = R'}$), e.g. $\ce{PhN=N–NPhMe}$, N-methyldiazoaminobenzene.
See also: triazenes