1. [n]  the Turkic language spoken by the Kazak people
2. [n]  a landlocked republic south of Russia and northeast of the Caspian Sea; the original Turkic-speaking inhabitants were overrun by Mongols in the 13th century; an Asian Soviet from 1936 to 1991
3. [n]  a member of a Muslim Turkic people of western Asia (especially in Kazakstan)

KAZAK is a 5 letter word that starts with K.