https://doi.org/10.1351/goldbook.A00564
Compounds having the structure $\ce{RN=CR2}$ ($\ce{R\neq H}$). Many consider the term to include the compounds $\ce{RN=CRH}$ ($\ce{R\neq H}$), thus making azomethines synonymous with Schiff bases.
See: imines, Schiff bases