a lake in Kazakhstan and Uzbekistan, east of the Caspian Sea, formerly the fourth largest lake in the world: shallow and saline, now badly polluted; use of its source waters for irrigation led to a loss of over 50% of its area between 1967 and 1997, after which the reduction began to be slowed. Area originally (to 1960) about 68 000 sq km (26 400 sq miles); water area reduced by 2004 to about17 158 sq km (6625 sq miles) and the lake divided into sections