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.
An isotope of hydrogen whose nucleus has one proton and one neutron and whose atomic mass is 2. Deuterium is used widely as a tracer for analyzing chemical reactions, and it combines with oxygen to form heavy water. Also called heavy hydrogen. See more at hydrogen.