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.
Ordinarily, the nucleus of a hydrogen atom consists of a single proton, but deuterium is an isotope of hydrogen that contains one neutron as well as one proton, vastly increasing the weight of the element and altering its atomic properties.Heavy water reactors offer some advantages over those that use normal, or light, water as a neutron moderator.