Cholesterol
Etymology
From Greek "chole" (bile) and "stereos" (solid), plus the chemical suffix "-ol," because it was first identified as a solid component of gallstones in the bile. The name records where scientists first found it, not what it does.
noun · /kuh-LES-tuh-rol/
A waxy fat the body needs to build cells and hormones, but which harms arteries in excess.
What it names
Use it for the essential-but-double-edged fat in your blood — vital in the right amount, dangerous in the wrong balance.
Example
His doctor was less worried about total cholesterol than about the ratio between the two kinds.
Related idea
The "good" and "bad" labels are about carriers, not the cholesterol itself: LDL tends to deposit it in artery walls, while HDL helps haul it away. Cholesterol is a distinct thing from triglycerides, the other blood fat, which store spare energy.