Condensation products, $\ce{R2C=NN=CR2}$, of two moles of a carbonyl compound with one
mole of
hydrazine (this term should not be confused with the ending -azine appearing in Hantzsch–Widman names for some heterocycles).
Source: PAC, 1995,
67, 1307. (
Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1321 [
Terms] [
Paper]