Terrorist group

Any number of terrorists who assemble together, have a unifying relationship, or are organized for the purpose of committing an act or acts of violence or threatens violence in pursuit of their political, religious, or ideological objectives. (JP 1-02).

Source: Terms & Definitions of Interest for DoD Counterintelligence Professionals, Office of the National Counterintelligence https://www.dni.gov/files/NCSC/documents/ci/CI_Glossary.pdf