An Etymological Dictionary of the German Language/Annotated/Holz
Holz, neuter, ‘wood, timber,’ from Middle High German and Old High German holz, neuter, ‘forest, thicket, timber.’ In the remaining dialects the meaning ‘forest’ preponderates. Compare Old Icelandic holt, neuter, ‘forest, thicket,’ so too Anglo-Saxon and Middle English holt, neuter, (wanting in English), but Dutch hout, ‘thicket, wood (as material).’ Teutonic type hultos, from pre-Teutonic kldos; compare Old Slovenian (with a different stage of gradation) klada, feminine, ‘beam, wood,’ Greek κλάδο-ς, masculine, ‘twig,’ Old Irish caill, coill, ‘forest’ (with ll from Id).