Any of a group of lipids derived from saturated compound called cyclopentanoperhydrophenanthrene, which has a nucleus of four rings (see formula). Some of the most important steroid derivatives are the steroid alcohols, or sterols. Other steroids include the bile acids, which aid digestion of fats in the intestine; the sex hormones (androgens and oestrogens); and the corticosteroid hormones, produced by the adrenal cortex. Vitamin D is also based on the steroid structure.
https://www.qmul.ac.uk/sbcs/iupac/steroid/3S01.html Information about IUPAC nomenclature