[1795–1805; un-1 + restraint]This word is first recorded in the period 1795–1805. Other words that entered Englishat around the same time include: kingpin, mirage, oxidize, steeplechase, wreckerun- is a prefix meaning “not,” freely used as an English formative, giving negative oropposite force in adjectives and their derivative adverbs and nouns (unfair; unfairly; unfairness; unfelt; unseen; unfitting; unformed; unheard-of; un-get-at-able), and less freely used in certain other nouns (unrest; unemployment)