Urdu (ōrˈdō) [key], language belonging to the Indic group of the Indo-Iranian subfamily of the Indo-European family of languages. The official tongue of Pakistan, Urdu is also one of the 15 languages recognized in the 1950 Indian constitution. Urdu has been described as the written or literary variant of Hindustani that is used by Muslims. It is written in a modified form of the Arabic alphabet, and its basically Indic vocabulary has been enriched by borrowings from Arabic and Persian. Grammatically and phonetically, however, Urdu is an Indic language. About 100 million persons in Pakistan and India understand Urdu.
See M. C. Saihgal, Hindustani Grammar (Urdu edition, 1945); E. Bender, Urdu Grammar and Reader (1967); F. Southworth, Student's Hindi-Urdu Reference Manual (1971); W. Bright and S. A. Kahn, The Urdu Writing System (1976).