An Etymological Dictionary of the German Language/eben
eben, adj., ‘even, level, plain, smooth,’ from MidHG. ëben, OHG. ëban, adj., ‘level, flat, straight’; common to Teut. under these meanings, but it is not found in any other Aryan group; comp. OSax. eƀan, Du. even, AS. ëfn, E. even, OIc. jafn, Goth. ibns, ‘level.’ Akin perhaps to Goth. ibuks, adj., ‘backward’ (see Ebbe). Apart from Teut. the stem ib in the form ep or ebh has not yet been authenticated; Lat. œ̂quus (Sans. êka), cannot, on account of phonetic differences, be regarded as a cognate. —
eben, adv., ‘even, just,’ from MidHG. ëbene, OHG. ëbano; comp. OSax. ëfno, AS. ëfne (whence E. even); the old adv. form of the adj. (Comp. neben.)