Definitions
1.nounThe chemical element (symbol O) with an atomic number of 8 and relative atomic mass of 15.9994. It is a colorless and odorless gas.
2.nounMolecular oxygen (O2), a colorless, odorless gas at room temperature, also called dioxygen.
3.nounA mixture of oxygen and other gases, administered to a patient to help them breathe.
4.nounAn atom of this element.