An Etymological Dictionary of the German Language/Annotated/un-
un-, prefix, ‘not,’ from the equivalent Middle High German and Old High German un-; a negative prefix common to Teutonic and Aryan; compare Old Saxon un-, Dutch on-, Anglo-Saxon and English un-, Old Icelandic ó-. Corresponding to Greek ἀ-, Latin in-, Sanscrit and Zend a-, an-. With this prefix is connected the common Aryan negation nē̆, ‘not’ (see nicht), as well as the preposition ohne and its cognates.