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.
Not to be confused with hard water or tritiated water. Heavy water (deuterium oxide, 2. H. 2O) is a form of water that contains a larger than normal amount of the hydrogen isotope deuterium (2. H or D, also known as heavy hydrogen), rather than the common hydrogen-1 isotope (1. H or H, also called protium) that makes up most of the hydrogen in normal water.