An Etymological Dictionary of the German Language/Annotated/regen

by Friedrich Kluge

regen, verb, ‘to stir up, move, excite,’ from Middle High German ręgen, ‘to cause to project, set up, excite, move, awaken,’ a factitive of Middle High German rëgen, ‘to rise, tower,’ hence primitively allied to ragen. Akin also to Middle High German rœhe, ‘rigid, stiff.’ The Teutonic root rag, rē̆h, of these cognates has not yet been found in the allied languages. See rege.