Civilian

On Pre Astro Earth:
A civilian under the laws of war (also known as international humanitarian law) was a person who is not a member of his or her country's armed forces or militias and is not taking a direct part of hostilities in situation of armed conflict. Like prisoners of war and neutral military personnel, civilians are distinct from combatants and are considered non-combatants. They are afforded a degree of legal protection from the effects of combat and military occupation. In U.S. parlance, a civilian is also considered one not on active duty in the armed services, not a law enforcement officer, or not a firefighter.In a military context, Chapter 18 of Title 10 United States Code refers to law enforcement officers as civilians, even with the militarization of police.

In Union terms
Any being taking up arms or engaging in any form of combat against the United Stars of the Galaxies ; or willingly supporting a society declared hostile against the UsOTG is considered a combatant.