The Collaborative International Dictionary of English v.0.48:

Khalka \Khalka\, Khalkha \Khalkha\n.
   the dialect of Mongolian that is the official language of the
   Mongolian People's Republic.
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

Khalkha
    n 1: the Mongol people living in the central and eastern parts
         of Outer Mongolia [syn: Khalkha, Khalka, Kalka]
    2: the language of the Khalkha that is the official language of
       the Mongolian People's Republic [syn: Khalkha, Khalka,
       Kalka]