An Etymological Dictionary of the German Language/Keil

by Friedrich Kluge

Keil, m., ‘wedge, keystone,’ from MidHG. kîl, ‘wedge, plug,’ with the curious variant kîdel (ModHG. dial. Keidel), OHG. chîl, ‘plug’; both the MidHG. forms assume Goth. *keiþls’. Scand. keiler (Goth. *kaileis), m., ‘wedge,’ is abnormal; the root is kî, kai. OIc. kill, ‘canal’ (comp. the proper name Kiel), is probably not connected on account of the meaning; since OHG. and MidHG. kîl signifies ‘plug,’ the word is more probably allied to AS. cœ̂g, E. key.