What does it mean if something is oxidized?
If a substance is oxidized it loses electron density to another substance.
Oxidation is named after Oxygen which has the second highest electronegativity of all the elements. Because Oxygen has a high electronegativity Oxygen draws electron density towards the Oxygen atom and away from the other substance.
In Oxidization the electron density of an atom, or substance is drawn away from the substance being Oxidized. The Oxidizing agent can be another substance other than Oxygen but always is a substance that has a greater electronegativity than the substance being oxidized.