What is Armed Forces?

Alternative Forms: Armed force
Legal Definition
The armed forces of a country are its government-sponsored defense, fighting forces, and organizations. They exist to further the foreign and domestic policies of their governing body and to defend that body and the nation it represents from external and internal aggressors. In broad usage, the terms "armed forces" and "military" are often treated synonymously, although in technical usage a distinction is sometimes made in which a country's armed forces may include both its military and other paramilitary forces. Armed force is the use of armed forces to achieve political objectives.

The study of the use of armed forces is called military science. Broadly speaking, this involves considering offense and defense at three "levels": strategy, operational art, and tactics. All three levels study the application of the use of force in order to achieve a desired objective.
-- Wikipedia
Legal Definition
a posse or a group of civilians that are armed and authorised by an official officer of the peace in the community to aid in capturing criminals and to prevent crime.