What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
1Chiefly Australian. A former convict, especially one who was transported or sentenced to penal servitude.
2A hardened or habitual prisoner; a recidivist. In extended use: = "old hand".
Early 19th century; earliest use found in James Vaux (1782–c1841). From old + lag.