Dr. S. W. Fallon's English Urdu Dictionary is a authentic source for Urdu language. This Dictionary features more then 75000 words with Urdu meanings.

This app also provides Urdu search facility. Urdu can be typed by using iOS provided Urdu keyboard which can be added from Settings > General > Keyboard > Keyboards > Add New Keyboard ... > Urdu

Three search modes: words starting letters, containing letters and Urdu search.