In chemistry, a trivial name is a nonsystematic name for a chemical substance. That is, the name is not recognized according to the rules of any formal system of chemical nomenclature such as IUPAC inorganic or IUPAC organic nomenclature. A trivial name is not a formal name and is usually a common name. Generally, trivial names are not useful in describing the essential properties of the thing being named. Properties such as the molecular structure of a chemical compound are not indicated. And, in some cases, trivial names can be ambiguous or will carry different meanings in different industries or in different geographic regions (for example, a trivial name such as white metal can mean various things). Trivial names are simpler. As a result, a limited number of trivial chemical names are retained names, an accepted part of the nomenclature. Trivial names often arise in the common language; they may come from historic usages in, for example, alchemy. Many trivial names pre-date the institution of formal naming conventions. Names can be based on a property of the chemical, including appearance (color, taste or smell), consistency, and crystal structure; a place where it was found or where the discoverer comes from; the name of a scientist; a mythological figure; an astronomical body; the shape of the molecule; and even fictional figures. All elements that have been isolated have trivial names. Definitions In scientific documents, international treaties, patents and legal definitions, names for chemicals are needed that identify them unambiguously. This need is satisfied by systematic names. One such system, established by the International Union of Pure and Applied Chemistry (IUPAC), was established in 1950. Other systems have been developed by the American Chemical Society, the International Organization for Standardization, and the World Health Organization. However, chemists still use many names that are not systematic because they are traditional or because they are more convenient than the systematic names. These are called trivial names. The word "trivial", often used in a pejorative sense, was intended to mean "commonplace". In addition to trivial names, chemists have constructed semi-trivial names by appending a standard symbol to a trivial stem. Some trivial and semi-trivial names are so widely used that they have been officially adopted by IUPAC; these are known as retained names. Elements Traditional names of elements are trivial, some originating in alchemy. IUPAC has accepted these names, but has also defined systematic names