Before me, on an otherwise healthy-looking piece of paper, I see in my own handwriting: "[chole]ster[e] [in][ol]oid." That is what I got for being nosy about the structure of the word "steroid." I knew all along that steroids are a complex matter, but at least the word could have been simple. It seems it is not.
I started out with the assumption that the word "steroid" has something to do with Greek stereos and the suspicion that the relationship is roundabout, for since stereos means "solid" and "-oid" suggests a deviation from the full meaning of what precedes, a steroid would be a sort-of-solid substance, which is obviously nonsense.
The actual chain is this: From Greek stereos the French built stérine by means of their suffix -ine. In the process they bracketed away an "e," otherwise they would have come up with stéréine. To this stér[é]ine they prefixed