The Collaborative International Dictionary of English v.0.48:

Gemel \Gem"el\, n.
   1. One of the twins. [Obs.] --Wyclif.
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   2. (Heb.) One of the barrulets placed parallel and closed to
      each other. Cf. Bars gemel, under Gemel, a.
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            Two gemels silver between two griffins passant.
                                                  --Strype.
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   Gemel hinge (Locksmithing), a hinge consisting of an eye or
      loop and a hook.

   Gemel ring, a ring with two or more links; a gimbal. See
      Gimbal.

   Gemel window, a window with two bays.
      [1913 Webster]