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 • Syn: oxygen, O • Derivationally related forms: oxygenate (for: oxygen), oxygenize (for: oxygen) • Hypernyms: chemical element, element, gas • Hyponyms: liquid oxygen, LOX • Substance Holonyms: water, H2O, air, ozone