MSH: A group of polycyclic compounds closely related biochemically to TERPENES. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (STEROLS), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. (From Hawley's Condensed Chemical Dictionary, 11th ed),CSP: compounds that contain a hydrogenated cyclopentanoperhydrophenanthrene ring system; they include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols, and certain natural drugs and poisons.,NCI: Any of a group of lipids (fats) that have a certain chemical structure. Steroids occur naturally in plants and animals or they may be made in the laboratory. Examples of steroids include sex hormones, cholesterol, bile acids, and some drugs.,MEDLINEPLUS: You may have heard about <a href='http://www.