Oxidation: Of Substrate By Reagent
A substrate is deemed to be oxidised by an oxidising agent if the oxidising agent (1) removes electrons by single electron transfer or SET, or (2) removes electron rich hydrogen from the substrate, or (3) removes electron density from the substrate by reversing polarisation by adding electronegative oxygen or (4) electronegative halogen atoms.

For more information look in the Chemogenesis webbook section on redox chemistry.