Divination or fortune-telling through the observation of heat generated by electrical currents (an archaic or fictional concept).
From electro- + -thermancy (from Greek therme, 'heat' + manteia, 'divination'). Follows the pattern of words like necromancy and geomancy, but is rarely if ever used in serious contexts.
This word is almost certainly academic whimsy—it follows proper word-formation rules in English but was never a real practice, showing how you can build plausible-sounding words that don't actually exist in real use.
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