The Collaborative International Dictionary of English v.0.48:

Topgallant \Top`gal"lant\, a.
   [1913 Webster]
   1. (Naut.) Situated above the topmast and below the royal
      mast; designatb, or pertaining to, the third spars in
      order from the deck; as, the topgallant mast, yards,
      braces, and the like. See Illustration of Ship.
      [1913 Webster]

   2. Fig.: Highest; elevated; splendid. "The consciences of
      topgallant sparks." --L'Estrange.
      [1913 Webster]

   Topgallant breeze, a breeze in which the topgallant sails
      may properly be carried.
      [1913 Webster]