[1615–25; appar. un-1 + sight, for expected unsighted]This word is first recorded in the period 1615–25. Other words that entered Englishat around the same time include: berth, deposit, facet, garrote, scintillationun- 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)