What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
Originally: characterized by or associated with the presence of dark pigment (specifically haemoglobin) in the urine. In later use also: of, relating to, or associated with melanuria.
Late 19th century; earliest use found in American Journal of the Medical Sciences. From melano- + -uric, after French mélanurique.