What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
A plant pigment usually isolated as a violet or brown chloride.
Mid 19th century; earliest use found in Robert Thomson (1810–1864), medical officer of health. From German Primulin from scientific Latin Primula, genus name + German -in, so called because it was first obtained from the roots of the cowslip, Primula veris.