An Etymological Dictionary of the German Language/empören

by Friedrich Kluge

empören, vb., ‘to excite, enrage, (refl.) to revolt,’ from MidHG. enbœren, OHG. (occurs only once) anabôren, ‘to raise’; akin to MidHG. bôr, m., ‘defiance, revolt.’ The origin of the cognates is uncertain, because it is difficult to determine whether the r is primitive or whether it is by a later change based upon s (z); with ber, ‘upper space’ — see empor — there seems to be a connection by gradation of u to au; ModHG. böse (OHG. bôsi) is not allied.