The Collaborative International Dictionary of English v.0.48:

Hindoostanee \Hin"doo*sta"nee\, Hindoostani \Hin"doo*sta"ni\,
Hindustani \Hin"du*sta"ni\, a. [Hind. Hind[=u]st[=a]n[imac] an
   Indian, fr. Hind. and Per. Hind[=u]st[=a]n India.]
   Of or pertaining to the Hindoos or their language. -- n. The
   language of Hindustan; the name given by Europeans to the
   most generally spoken of the modern Aryan languages of India.
   It is Hindi with the addition of Persian and Arabic words.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Hindoostani
    n 1: a form of Hindi spoken around Delhi [syn: Hindustani,
         Hindoostani, Hindostani]