clev·is /ˈklɛvəs/
 U形夾
 Clev·is n.  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.
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 clevis
      n : 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.