A mare (mære, mare, ; mara in Old High German, Old Norse, and Swedish) is a malicious entity in Germanic and Slavic folklore that walks on people's chests while they sleep, bringing on nightmares. The word mare comes (through Middle English mare) from the Old English feminine noun mære (which had numerous variant forms, including mare, mere, and mær). These in turn come from Proto-Germanic *marōn. *Marōn is the source of mara, from which are derived mara; mara; marra; mare; mare/mara, Dutch: (nacht)merrie, and German: (Nacht)mahr. The -mar in French cauchemar ('nightmare') is borrowed from the Germanic through Old French mare. Most scholars trace the word back to the reconstructed Proto-Indo-European root *mer-, associated with crushing, pressing and oppressing. or according to other sources 'to rub away' or 'to harm'. However, other etymologies have been suggested. For example, Éva Pócs saw the term as being cognate with the Greek μόρος (Indo-European *móros), meaning 'doom'. There is no definite answer among historians about the time of origin of the word. According to the philologist Yeleazar Meletinsky, the Proto-Slavonic root mara passed into the Germanic language no later than the 1st century BC. In Norwegian and Danish, the words for 'nightmare' are mareritt and mareridt respectively, which can be directly translated as 'mare-ride'. The Icelandic word martröð has the same meaning (-tröð from the verb troða, 'trample', 'stamp on', related to tread), whereas the Swedish mardröm translates as 'mare-dream'. The mare was believed to ride horses, which left them exhausted and covered in sweat by the morning. She could also entangle the hair of the sleeping man or beast, resulting in "marelocks", called marflätor ('mare-braids') or martovor ('mare-tangles') in Swedish or marefletter and marefloker in Norwegian. The belief probably originated as an explanation to the Polish plait phenomenon, a hair disease. Even trees were thought to be ridden by the mare, resulting in branches being entangled.