Dehradun (dâr´ədōōn), city (1991 pop. 270,000), capital of Uttarakhand state, N central India. It is a rail terminus from the S for Mussoorie, a summer hill resort. Tea processing is the main industry. In Dehradun is the Indian military academy and an institute for forestry research, with an associated museum and botanical garden. The temple (1699) of Ram Rai, founder of the Hindu Udasi sect of ascetics, is the city's most notable historical building.