An Etymological Dictionary of the German Language/jener
jener, pron., ‘you, yonder, that, the former,’ from the equiv. MidHG. jęner, OHG. jęnêr, allied to the differently vocalised Goth. jains, OIc. enn, inn, AS. geon, E. you (with which yonder is connected). In late MidHG. dër jęner, ‘that,’ is also used, whence ModHG. derjenige. —