The Collaborative International Dictionary of English v.0.48:

Doni \Do"ni\, n. [Tamil t?n[imac].] (Naut.)
   A clumsy craft, having one mast with a long sail, used for
   trading purposes on the coasts of Coromandel and Ceylon.
   [Written also dhony, doney, and done.] --Balfour.
   [1913 Webster]