Cahoot is a word meaning "partnership" that curiously almost never shows up in its singular form. We only ever see the term as part of the phrase in cahoots (which has more negative, conspiratorial connotations), which traces back to the mid-eighteenth century. Cahoot was around for a little bit before that, with its first attestation in an 1829 grammar book, but it eventually faded as the expression stayed prominent. Linguists aren't quite sure where that comes from, because it seems like it popped out of nowhere in the American south, but the main (tenuous) theory right now is that cahoot came from the French word cahute, meaning "hut" (maybe partnerships were formed. That's from Dutch kajuit, which is from Middle Dutch kayhute, which also has an unknown origin.
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.