Yule, Henry, and A. C. Burnell. Hobson-Jobson: The Anglo-Indian Dictionary. 1996 reprint ed. Ware, Hertfordshire: Wordsworth Reference, 1886.
A classic look at Indian words that have influenced English and the slang of the British Raj. A searchable, online version is available through the University of Chicago.
While the original edition is available online, Oxford University Press has published a newly edited edition of Yule and Burnell’s work. It’s a somewhat abridged version of the original, but contains notes and editorial commentary.
Copyright 1997-2017, by David Wilton