1historical The period of violent repression led by counter-revolutionary forces in 1795, in reaction to the First French Revolution; the violence and bloodshed of this period. Also: the (period of) repression following the restoration of Louis XVIII in 1815.
2Any of various periods of violent repression, especially one led by conservative or reactionary forces against a communist or left-wing regime.
Sometimes with specific reference to the persecution of supporters of the revolution during the Russian Civil War (1917–22); to the campaign of violence carried out by counter-revolutionaries in Hungary between 1919 and 1921; or to periods of violent repression in mainland China in the years following 1927 and in Taiwan after 1949.
Early 19th century; earliest use found in Sketch Present State France. From white + terror.