1) Co 1) Oxide 
A monoxide is any oxide containing just one atom of oxygen in the molecule. For example, Potassium oxide (K2O), has only one atom of oxygen, and is thus a monoxide. Water (H2O) is also a monoxide; see dihydrogen monoxide hoax. A well known monoxide is carbon monoxide (CO); see carbon monoxide poisoning. Most of the members of the Periodic Table fo...
• (n.) An oxide containing one atom of oxygen in each molecule; as, barium monoxide.
Mo·nox'ide noun [ Mon- + oxide .] (Chemistry) An oxide containing one atom of oxygen in each molecule; as, barium monoxide . 
Type: Term Pronunciation: mon-ok′sīd Definitions: 1. Any oxide with only one atom of oxygen, CO.
[n] - an oxide containing just one atom of oxygen in the molecule
noun an oxide containing just one atom of oxygen in the molecule
an oxide containing one oxygen atom in each molecule.