This term systematically means carbenes bearing an imino or
N-substituted imino group,
RN=, somewhere in the molecule. E.g.
R–C:–CH2C(=NR)R. It is listed here in order to warn against its misuse for alkylideneamino carbenes.
See: carbenes, nitrile ylides
Source:
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1343 (https://doi.org/10.1351/pac199567081307)