An Etymological Dictionary of the German Language/Lachs

by Friedrich Kluge

Lachs, m., ‘salmon,’ from the equiv. MidHG. lahs (plur. lęhse), OHG. lahs; corresponding to AS. leax, OIc. lax, Scotch lax; a common and prim. Teut. term for ‘salmon’; in Goth. perhaps *lahs. The Slav. and Lith. words are cognate; Lith. lasziszà, Lett. lasis, Russ. lososŭ, ‘salmon trout,’ Pol. lasóš, ‘salmon.’ Hence the s in OHG. lahs is a suffix (comp. Fuchs), and not a part of the root.