Definitions for "Cossacks"
A special caste with a strong military (but also communal-democratic) tradition. They were used by the tsarist regime as auxiliaries of the police against strikes and demonstrations. Although they consider themselves as a separate race, the Cossacks are in fact Russians and Ukrainians, the descendants of runaway serfs who made their homes in the wild frontier areas to Russia’s South and East where they were frequently at war with Russia’s enemies, the Poles and Turks.
Peasants recruited to migrate to newly seized lands in Russia, particularly in south; combined agriculture with military conquests; spurred additional frontier conquests and settlements. (p. 567)
Keywords:  ivan, outlaw, armies, escape, attempt
free groups and outlaw armies that were formed to fight Ivan in an attempt to escape his rule. (p. 580)