O 酸素 ａ
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
2価の非金属元素で、通例無色、無臭、無味の不燃性の二原子気体 体積で大気の28％を占める 地球の地殻の中に最も豊富に含まれる