- oxygen, O, atomic number 8 - a nonmetallic bivalent element that is normally a colorless odorless tasteless nonflammable diatomic gas; constitutes 21 percent of the atmosphere by volume; the most abundant element in the earth's crust
--1 is a kind of chemical element, element; gas
--1 is a substance of water, H2O; air; ozone
--1 has particulars: liquid oxygen, LOXDerived forms: verb oxygenate1, verb oxygenize2, verb oxygenize3