An Etymological Dictionary of the German Language/Annotated/kennen
kennen, verb, ‘to know, be acquainted with,’ from the equivalent Middle High German kęnnen, Old High German chęnnen. The simple form was very little used in Middle High German and Old High German, the usual words being the compounds Old High German irchęnnen, Middle High German erkęnnen, and Old High German bichęnnen, Middle High German bekęnnen, with the meanings of Modern High German kennen. The corresponding Gothic kannjan (uskannjan), as well as Anglo-Saxon cęnnan, gecęnnan, signifies ‘to make known.’ This double sense, which is combined in Old Icelandic kenna, is explained by the fact that Old Teutonic kannjan is a factitive of the Old Teutonic preterite-present kann, infinitive kunnan, ‘to know’; erkennen is a derivative ‘to inform oneself.’ Compare further references under können.