What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
Cholesterol.
Early 19th century; earliest use found in Annals of Philosophy. From French cholestérine (M. E. Chevreul 1816, in Ann. de chim. et de physique 2 346; from ancient Greek χολή bile + στερεός stiff, solid + French -ine); in some forms with suffix substitution.