gyassa

noun1

1. •
   A sail trading vessel of the upper Nile, with one mast and a very large lateen sail on a yard twice as long as the mast and as long as, or longer than, the vessel itself.

   • What was worse, the gyassa , laden with stores and spare kits, belonging to an Egyptian battalion which was just about to start forward, was blown clean over, and everything shot into the river. — 1898