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.
Early 19th century; earliest use found in Sketch Present State France. From white + terror.