Dictionary.net

the office that serves as the administrative center of an enterprise

the military installation from which a commander performs the functions of command; "his headquarters were a couple of large tents"

(usually plural) the military installation from which a commander performs the functions of command; "the general's headquarters were a couple of large tents"

(plural) a military unit consisting of a commander and the headquarters staff

The office or residence of an official; a center of authority.

The quarters or residence of a commander-in-chief or general.

The location of a commanding officer in camp, garrison, etc.

The place of general rendezvous, or lodgment for soldiers; where the commander in chief takes up his quarters.