What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
Originally: †inflammation of the peripheral portion of the optic disc or of the adjacent retina (obsolete). In later use: inflammation of the perineurium of a nerve or nerves.
Late 19th century; earliest use found in The Lancet. From peri- + neuritis. In later use after perineurium.