Definition of tankie:
(n) :
(politics, slang, derogatory, by extension) A supporter of policies and actions by the Soviet Union, China, Cuba or other authoritarian socialist (chiefly Marxist-Leninist) governments.
(adj) :
(politics, slang, derogatory) Supporting the policies of the Soviet Union or other Marxist-Leninist governments.
(n) :
(UK, politics, slang, historical) A member of the Communist Party of Great Britain who supported the Soviet Union's policy of crushing revolts in Hungary in the 1950s and Czechoslovakia in the 1960s by sending tanks into those countries.
(n) :
(military, slang) A soldier from a tank regiment.
(n) :
(rail transport, slang) A tank engine.