Deoxygenation is a chemical reaction involving the removal of oxygen atoms from a molecule. The term also refers to the removal molecular oxygen (O2) from gases and solvents, a step in air-free technique and gas purifiers. As applied to organic compounds, deoxygenation is a component of fuels production as well a type of reaction employed in organ...
Reduction in the dissolved oxygen content of a water, caused by hot weather or the introduction of pollutants such as sewage. Excessive deoxygenation is fatal to fish.
• (n.) The act or operation of depriving of oxygen.
(de-ok″sĭ-jәn-a´shәn) the act of depriving of oxygen.
De·ox`y·gen·a'tion noun (Chemistry) The act or operation of depriving of oxygen. 
In chemistry, deoxygenation is the process of removing water from a compound.