noun. A mixture of butter and suger. A mixture of butter and suger. The definition of a mixture is a combination of different things, or the state or act of being mixed. 1  An example of a mixture is a bowl of butter, sugar and salt. 2  An example of mixture is the process of combining flour and baking soda.
deuterium oxide. An isotope of water in which hydrogen has been displaced by its isotope deuterium. Its properties differ from ordinary water in that it has higher freezing and boiling points and is incapable of supporting life.
Deuterium is an isotope of the element hydrogen with a nucleus consisting of one proton and one neutron. This gives deuterium twice the atomic mass of ordinary hydrogen, which contains one proton and no neutrons. Deuterium has an atomic weight of 2.014, almost twice the weight of ordinary hydrogen.