The term "steroid" originates from the scientific name "sterol," which was coined in the early 20th century from the Greek stereos (solid) because sterols were first isolated from gallstones, a solid bodily substance. The suffix "-oid" (resembling) was added to create a class name for compounds chemically similar to sterols. The modern, broadened meaning encompasses a vast family of biologically active lipids with a characteristic four-ring carbon structure, whose solid, stable molecular framework underpins their diverse functions in physiology and medicine.

Structure: ster (solid) + oid (resembling) + s (plural suffix) - ster: From Greek stereos, meaning "solid, firm, three-dimensional". In this word, it refers to the solid, rigid structure of the steroid molecule's core. - oid: A suffix from Greek -oeidēs, meaning "resembling, having the form of". It indicates that the compound is like or derived from the sterol structure. - s: A plural suffix from Old English, indicating more than one.