Source : Webster's Revised Unabridged Dictionary (1913)

Backsheesh \Back"sheesh`\, Backshish \Back"shish`\, n. [Pers.
   bakhsh[=i]sh, fr. bakhsh[=i]dan to give.]
   In Egypt and the Turkish empire, a gratuity; a ``tip''.

Source : WordNet®

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