An Etymological Dictionary of the German Language/Spiegel
Spiegel, m., ‘mirror, looking-glass, reflector,’ from the equiv. MidHG. spiegel, OHG. spiagal, m. (comp. Du. spiegel). The OHG. term is derived, with a change of gender, from MidLat. spêgulum (equiv. to Lat. spĕculum), to which Ital. speglio (also specchio), ‘mirror,’ points. The word must have been borrowed, on account of the change of vowels, prior to the OHG. period. OTeut. has a peculiar word for ‘mirror’; comp. OHG. scûchar, lit. ‘shadow container,’ from OHG. scûwo, AS. sčûa, ‘shadow,’ in Goth. skuggwa, ‘mirror.’