Meaning

1. A member or descendant of an originally (semi-)nomadic population of Eastern Europe and the adjacent parts of Asia, formed in part of runaways from neighbouring countries, that eventually settled in parts of the Polish-Lithuanian Commonwealth and the Russian tsarist Empire and constituted a military caste, particularly in areas now comprising southern Russia and Ukraine.
2. A member of a military unit (typically cavalry, originally recruited exclusively from the above).
3. (obsolete) A Ukrainian.
4. A mercenary; a regular or irregular soldier employed to persecute or oppress disfavoured groups, or in massacres of such groups, such as in anti-Jewish pogroms; a police officer or private security guard, particularly one used in strike-breaking; a violent thug.
5. A mercenary; a regular or irregular soldier employed to persecute or oppress disfavoured groups, or in massacres of such groups, such as in anti-Jewish pogroms; a police officer or private security guard, particularly one used in strike-breaking; a violent thug.