Civilian
From Halopedia, the Halo wiki
A Civilian, according to international humanitarian law, is a person who is not a member of his or her country's armed forces. The term is also often used colloquially to refer to people who are not members of a particular profession or occupation, especially by law enforcement agencies, which often use rank structures similar to those of military units. Often, the military's main purpose and occupation is to defend the civilians from invaders. However, many civilians, such as Dr. Halsey are involved with the military. So far, extremely few have been seen in any of the Halo games. Except for the factory workers, the garb, appearance, or personality of any civilian, alien or human, has never been completely divulged.