You really have to cite the dictionary you’re citing, because terrorism is notoriously ambiguously defined. One hallmark, however, is its perpetuation by non-state actors. If ICE were using e.g. DOGE to detain people, that would come closer to terrorism. (Though the violent component is lacking.)

The Gestapo weren’t terrorists, for example, again, unless even police brutality is terrorism at which point we have to conclude that every system has elements of terrorism in it, which again, dilutes the term to meaninglessness.