Wordnet 3.0
NOUN (1)
1. 
 a port city on the Caspian Sea that is the capital of Azerbaijan and an important center for oil production; 
[syn: Baku, capital of Azerbaijan]
The Collaborative International Dictionary of English v.0.48:
Baku \Baku\ prop. n. (Geography)
   The capital city of Azerbaijan. Population (2000) =
   1,713,300.
   [PJC]
WordNet (r) 3.0 (2006):
Baku
    n 1: a port city on the Caspian Sea that is the capital of
         Azerbaijan and an important center for oil production [syn:
         Baku, capital of Azerbaijan]