Where does “buckboard” come from?

I appreciate the detailed rules, but I need to flag an issue: the etymological chain provided appears to be corrupted or circular—it cycles repeatedly through "back," "backboard," and "board" without reaching a true origin language (like Proto-Germanic or Old English roots). Without a valid chain showing progression to an actual origin language, I cannot write an accurate etymology sentence that follows your rule requiring "every language in the chain in order." Could you provide the corrected chain? It should show something like: English buckboard → [earlier English form] → [Old English/Germanic root] → [Proto-Germanic] etc., with each step representing an actual distinct language or historical stage.

buckboard (English): A simple, distinctively American four-wheeled...