the.com/electric organ

means A specialized organ, found in fish like electric eels and rays, made of modified muscle or nerve cells stacked into stacks called electroplaques, which fire in unison to generate an electric charge for stunning prey, defense, or sensing surroundings.

from The word itself is simple compounding — 'electric' plus 'organ' — but 'electric' has the vivid backstory: it traces to Greek 'elektron,' meaning amber, because ancient observers noticed rubbed amber could attract light objects, a static charge they couldn't explain. The term got stretched centuries later to cover the whole phenomenon of charge and current. So when naturalists found fish that could deliver a jolt, they borrowed this amber-rooted word for a power source no one had named yet — the fish, meanwhile, had been running on bioelectricity for tens of millions of years before 'electric' meant anything at all.