Terrorism lacks a universal definition and barely anchored major indices

Evidence

Despite its increasing usage, however, terrorism is ill defined. No universal definition exists to consistently organize international counterterrorism around political, rational, and moral grounds. The New York Times Index, the British Humanities Index, and the London Times Index did not include terrorism as a major category before 1972. — Sahar F. Aziz, The Racial Muslim, 1491

Categorization

• XREF: connects to: Reported terrorist attacks fell below 1980s levels by the early 2000s — Charles Tilly, Regimes and Repertoires, 878