https://doi.org/10.1351/goldbook.I02960
This term systematically means carbenes bearing an imino or N-substituted imino group, $\ce{RN=}$, somewhere in the molecule. E.g. $\ce{R–C:–CH2C(=NR)R}$. It is listed here in order to warn against its misuse for alkylideneamino carbenes.
See: carbenes, nitrile ylides