An obsolete term for oximes, based on the fact that compounds with a nitroso group,
–N=O, bonded to a
–CR2H group readily tautomerize to oximes.
Source:
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1345 (https://doi.org/10.1351/pac199567081307)