The Collaborative International Dictionary of English v.0.48:

Baksheesh \Bak"sheesh`\, Bakshish \Bak"shish`\, n.
   Same as Backsheesh.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

baksheesh \baksheesh\ n.
   1. A relatively small amount of money given for services
      rendered (as by a waiter). Same as Backsheesh.

   Syn: gratuity, tip, bakshish, bakshis, backsheesh.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

baksheesh
    n 1: a relatively small amount of money given for services
         rendered (as by a waiter) [syn: gratuity, tip,
         pourboire, baksheesh, bakshish, bakshis,
         backsheesh]