1917 20 Feb. 1/6 The holding of American ships in port by the terror threats of Germany.
1920 14 Dec. 1/7 (heading) All lines to Dublin cut. Irish capital isolated; new terror threat.
2006 J. Updike i. 43 The Secretary for Homeland Security upgrades the so-called terror-threat level from yellow, meaning merely ‘elevated’, to orange, meaning ‘high’.