An archaic or extremely rare optical instrument or measurement device, possibly for measuring distance or magnification, though documentation is limited.
From Greek apo- 'away' + metron 'measure' + -meter 'measuring device.' Likely a 19th-century coinage combining Greek elements for an instrument measuring something at a distance.
This word is so obscure that it barely appears in historical records—it's the kind of specialized scientific term that was invented for one specific instrument and then forgotten when technology advanced.
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