[ Iso- + nitroso-. ] (Chem.) A combining form (also used adjectively), signifying: Pertaining to, or designating, the characteristic, nitrogenous radical, NOH, called the isonitroso group. [ 1913 Webster ]
(Chem.) A prefix (also used adjectively) designating the group or radical -NO, called the nitroso group, or its compounds. [ 1913 Webster ]