We are ALL civilians. It's not an epithet.
http://en.wikipedia.org/wiki/Civilian
A civilian under international humanitarian law is a person who is not a member of his or her country's armed forces
Militia Act 1903 said:Composition of militia, and classification as organized militia and reserve militia.
Be it enacted, &.c, That the militia shall consist of every ablebodied male citizen of the respective States, Territories, and District of Columbia, and every able-bodied male of foreign birth who has declared his intention to become a citizen, who is more than eighteen and less than forty-five years of age, and shall be divided into two classes- the organized militia, to be known as the National Guard of the State, Territory, or District of Columbia, or by such other designations as may be given them by the laws of the respective States or Territories, and the remainder to be known as the Reserve Militia.
Civilian seems to be a term for those countries with subjects. Here in the federation almost everyone is in the militia, therefore in the armed forces and not civilian; congress just removed to requirement to have a musket or rifle when things were reorganized.