An Etymological Dictionary of the German Language/Annotated/gewöhnen
gewöhnen, verb, ‘to accustom, inure, habituate,’ from the equivalent Middle High German gewęnen, Old High German giwęnnan (preterite giwenita); corresponding to Dutch gewennen, Anglo-Saxon gewęnnan, Old Icelandic venja, Gothic wanjan, ‘to accustom’; derived from an old adjective or rather participle wana-, ‘accustomed’ (Old Icelandic vanr); for this word a parallel form was chiefly used, the latest derivative of which is gewohnt, ‘accustomed,’ Old High German giwon, Middle High German gewon, whence, with a dental suffix (see Mond and Habicht), Modern High German gewohnt (yet without t, Gewohnheit and gewöhnlich); allied to Old High German giwona, Middle High German gewone (gewan), ‘custom.’ For details see wohnen.