Compounds having the structure $\ce{R2C=NNR2}$, formally derived from
aldehydes or
ketones by replacing $\ce{=O}$ by $\ce{=NNH2}$ (or substituted analogues).
Source: PAC, 1995,
67, 1307. (
Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1341 [
Terms] [
Paper]