'Reign of Terror' definitions:

Definition of 'reign of terror'

noun

Any period of brutal suppression thought to resemble the Reign of Terror in France

noun

The historic period (1793-94) during the French Revolution when thousands were executed; "the Reign of the Bourbons ended and the Reign of Terror began"

Definition of 'Reign of Terror'

From: GCIDE

Terror \Ter"ror\, n. [L. terror, akin to terrere to frighten, for tersere; akin to Gr. ? to flee away, dread, Skr. tras to tremble, to be afraid, Russ. triasti to shake: cf. F. terreur. Cf. Deter.]
1. Extreme fear; fear that agitates body and mind; violent dread; fright. [1913 Webster]
Terror seized the rebel host. --Milton. [1913 Webster]
2. That which excites dread; a cause of extreme fear. [1913 Webster]
Those enormous terrors of the Nile. --Prior. [1913 Webster]
Rulers are not a terror to good works. --Rom. xiii. 3. [1913 Webster]
There is no terror, Cassius, in your threats. --Shak. [1913 Webster]
Note: Terror is used in the formation of compounds which are generally self-explaining: as, terror-fraught, terror-giving, terror-smitten, terror-stricken, terror-struck, and the like. [1913 Webster]
King of terrors, death. --Job xviii. 14.
Reign of Terror. (French Hist.) See in Dictionary of Noted Names in Fiction. [1913 Webster]
Syn: Alarm; fright; consternation; dread; dismay. See Alarm. [1913 Webster]