What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
(Now chiefly in Marxist theory): the value of a product or commodity as determined by its utility to the society in which it exists, as opposed to its value when traded or the quantity of other commodities for which it can be traded.
Mid 19th century; earliest use found in Thomas De Quincey (1785–1859), essayist.