o [ əu ]

• n.
  • 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

    同义词： oxygen atomic number 8

  • the 15th letter of the Roman alphabet

    同义词： letter o

  • the blood group whose red cells carry neither the A nor B antigens

    "people with type O blood are universal donors"

    同义词： type O group O

以上来源于: WordNet