monoxide

from WordNet (r) 3.0 (2006)

monoxide
    n 1: an oxide containing just one atom of oxygen in the molecule

from The Collaborative International Dictionary of English v.0.48

Monoxide \Mo*nox"ide\, n. [Mon- + oxide.] (Chem.)
   An oxide containing one atom of oxygen in each molecule; as,
   barium monoxide.
   [1913 Webster]