An Etymological Dictionary of the German Language/Annotated/lau
lau, adjective, ‘lukewarm, tepid,’ from the equivalent Middle High German lâ (inflected lâwêr), Old High German lâo (inflected; probably for an earlier *hlâo (Gothic *hlêws); compare Old Icelandic hlýr, ‘warm, mild,’ Dutch lauw. In the non-Teutonic languages indubitable cognates are wanting, yet the Romance cognates of flau (French flou) are derived from Old German.