From the linguistic experts at the University of Chicago, this is a wonderful compendium of online multilingual dictionaries of South Asian languages (including Iran and Afghanistan): http://dsal.uchicago.edu/dictionaries/
It includes dictionaries for Hindi, Urdu, Bengali, Tamil, Sanskrit, Pashto, Persian, Nepali, and more! It's a great reference tool, and fascinating to browse.
From the official description of the site:
"The South Asia Language and Area Center at University of Chicago, Columbia University, and the Triangle South Asia Consortium in North Carolina are creating and disseminating electronic dictionaries. For each of the twenty-six modern literary languages of South Asia, a panel of language experts identified key dictionaries currently in print and selected at least one multilingual dictionary for each language. For the more frequently taught languages, a monolingual dictionary also has been chosen. After identifying the best available resources, the chosen dictionaries have been converted to digital formats."