A name of a chemical, no part of which is necessarily used in a systematic sense; i.e., it gives little or no indication as to chemical structure. Such names are common for drugs, hormones, proteins, and other biologicals, and are used by the general public. They may not be officially sanctioned, in contrast to nonproprietary names, but may be adopted as official nonproprietary names as a result of widespread usage. Examples are water, aspirin, chlorophyll, heme, methotrexate, folic acid, caffeine, thyroxine, epinephrine, barbital, etc.; also common abbreviations for chemically defined substances, such as ACTH, MSH, BAL, DDT, which are spoken as such and not in terms of the words they represent. The distinction between trivial and semitrivial names is seldom made; thus tetrahydrofolate, methylglycine, glucosamine, etc., are often termed trivial even though each contains a systematic part that is used in the correct systematic sense (tetrahydro for four hydrogen atoms, methyl for a -CH3 group, amine for -NH2 in the above examples). Trivial names are often assigned arbitrarily to chemical compounds, especially from natural sources, before the chemical structures, hence systematic names can be assigned. Additionally, they afford useful shortenings of long systematic names even when these can be stated (although most such shortenings turn out to be semisystematic, because they incorporate some portion of the systematic name).