a coupler shaped like the letter U with holes through each end so a bolt or pin can pass through the holes to complete the coupling; used to attach a drawbar to a plow or wagon or trailer etc.
source: WordNet 3.0
A piece of metal bent in the form of an oxbow, with the two ends perforated to receive a pin, used on the end of the tongue of a plow, wagen, etc., to attach it to a draft chain, whiffletree, etc.; -- called also clavel, clevy.
