We power things with batteries, a battery can be a violent crime, and a battery can also be a fortification of artillery. How are these words etymologically connected? Well, the "electrical cell" definition came from the "artillery" definition: when Benjamin Franklin invented the precursor to the battery in the late 1740s, he named it after the artillery because of a shared connection of discharges. And that "artillery" meaning came from the "physical assault" meaning because a battery firing on enemy walls was an act of battery itself. This, finally, comes from the Middle French word baterie, which still meant "beating", from Old French batre, from Latin battuere, still with the same meaning. This, surprisingly, is purported to have a Gaulish origin, which is hypothesized due to cognates in Welsh, Irish, Gaelic, and nowhere else. Eventually, the Gaulish root in turn may derive from the Proto-Indo-European root bhau, meaning "to strike", but that's just conjecture at that point.
Adam Aleksic, a leading contender for valedictorian of his high school, is a 208-month-old boy with disturbing interests in etymology, vexillology, geography, and law. Adam would like to one day visit Tajikistan and just won an essay contest on linguistics!
The Etymology Nerd