English Reference
noun

terrorism

n.
US /ˈtɛɹɝˌɪzəm/ UK /tˈɛɹəɹˌɪzəm/ ter·ror·ism UK spelling terrorisms

  1. 01 B2 Upper Intermediate

    the use of violence or threats to scare people and force a government to change its actions.

    the unlawful use of force or violence against persons or property to intimidate or coerce a government or civilian population in furtherance of political or social objectives.

    Simple

    The government increased security at the airport to prevent acts of terrorism.

    In context

    International cooperation is essential to dismantle the financial networks that sustain global terrorism and radicalization.

    Usage

    Uncountable in general use; may be used as a countable noun when referring to specific types or instances.

  2. 02 C2 Proficiency AcademicFormal

    the period of extreme violence during the French Revolution.

    the specific historical period of state-sanctioned violence and mass executions during the French Revolution (1793–1794).

    Simple

    Historians study the origins of modern terrorism by looking back at the French Revolution.

    In context

    The term originally described the state-led terrorism of the Revolutionary tribunal against perceived enemies of the Republic.

    Usage

    Usually capitalized as 'the Terror' when referring specifically to the French historical event.

    Teacher's tip

    This historical sense is rare in daily conversation but common in university-level history or political science contexts.

    reign of terror

An attack on a Barclays Bank by five people from the Palestine Action group will not be treated as terrorism when they are sentenced, a judge has ruled.

The Guardian· 21 Aug 2026

He explained that Bowie, an Albany resident, was a “frequent social media user” who created over a dozen accounts “relaying support for terrorism”.

Al Jazeera· 20 Aug 2026

From French terrorisme, from terreur + -isme. By surface analysis, terror + -ism. The word first appears in English in 1795 in reference to the Jacobin radicals of France, who ruled during the Reign of Terror.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Level B2 · Upper Intermediate
Frequency Common
Updated