Initially applied only to the action of instilling terror into civilian populations in order to achieve political goals. Today terrorism is used as a derogatory propaganda tool, to dehumanize and demonize the tactics of impoverished opponents of colonialism, to deny them the use of rational political justification and motivation, allowing the labeller to ignore any need to deal with the "terrorist's" grievances and demands. Today the label "terrorism" is used by governments to describe anybody opposing the policies of the labeller (or their chosen partners) no matter how invidious those policies may be, even when the opposition is employed against military forces by completely legitimate guerilla forces.
"Terrorism is the war of the poor, and war is the terrorism of the rich." Peter Ustinov