In history and political science, to purge is to remove people considered by the group in power to be "undesirable" from a government, political party, a profession, or from community or society as a whole, often by violent means. Restoration of people from a purge is known as rehabilitation.
Notable purges in history
The purge has been a political tool throughout recorded history.
Rome
In the era of Republican Rome, Gaius Marius proscribed Sullan supporters after he and Cinna ousted Gnaeus Octavius; Sulla followed with even more brutal proscriptions against Marian supporters when he came into the dictatorship. The Second Triumvirate instituted more proscriptions some forty years afterward after taking control of Rome from Caesar's murderers.
England
The earliest use of the term itself was the English Civil War's Pride's Purge. In 1648, the moderate members of the English Long Parliament were purged by the army. Parliament would suffer subsequent purges under the Commonwealth