Definition of: oxidation

(ok′sə·dā′shən) noun Chem.
1. The act of uniting or of causing a substance to unite with oxygen.
2. The state of being so united.
3. Any changes in an element or a compound that result in addition to it of a negative radical or a relative decrease of the positive constituent.
4. The process by which the atoms of an element lose electrons: opposed to reduction.
—ox′i·da′tive adjective