The Collaborative International Dictionary of English v.0.48:

Doha \Doha\ prop. n. (Geography)
   The capital city of Qatar. Population (2000) = 300,000.
   [PJC]

WordNet (r) 3.0 (2006):

Doha
    n 1: the capital and chief port of Qatar [syn: Doha, Bida,
         El Beda, capital of Qatar]