Source : Webster's Revised Unabridged Dictionary (1913)

Primage \Pri"mage\ (?; 48), n. [F.] (Com.)
   A charge in addition to the freight; originally, a gratuity
   to the captain for his particular care of the goods
   (sometimes called {hat money}), but now belonging to the
   owners or freighters of the vessel, unless by special
   agreement the whole or part is assigned to the captain.
   --Homans.