Strongly motivated or energized into taking action; or coated with zinc to prevent rust (the original technical meaning).
From Luigi Galvani, an 18th-century scientist who discovered electrical current in living tissue. The zinc-coating meaning came from electroplating technology he helped inspire.
Luigi Galvani discovered electricity by accident — he noticed a dead frog's legs twitched when touching different metals, which launched the entire field of electrochemistry and got his name on everything from galvanized steel to galvanometers.
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