Condensation products, 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).
See also: aldazines, ketazines
PAC, 1995, 67, 1307 (Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1321