Liquidate is such an interesting word. It can mean "convert into cash", "pay off", or "murder", and all of those definitions come from an original meaning of "reduce to order" (whether it be an account or a life), first attested around 1575 by politician James Balfour in a legal context. He took it from Latin liquidare, which meant "to melt" but could also have a more metaphorical denotation of "clarify", which is what was extended to English. You might have guessed where this is going: the root in liquidare is liquidus, which meant "liquid" and indeed is the etymon of our word liquid (through Old French liquide). That traces further back to Proto-Italic wlikweo, which derives from the Proto-Indo-European reconstruction wleyk, meaning "to run" or "to flow". Usage of liquidate peaked in World War II (when the "assassinate meaning was at its greatest use) and has declined since.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.