Military. spec. A member of an organized military company or force, formed by voluntary enrolment and distinct from the regular army. In later use…

In the Ottoman Empire: a soldier belonging to the military reserve; (also) the military reserve itself.

U.S. (A name for) a volunteer militia force formed to protect a particular region; spec. one allied to the Confederate or Union armies during the…

A member of the (esp. military) reserve forces.

A member of a reserve force, a reservist.

a member of the Territorial Army or other voluntary armed force.

With the sense ‘carrying out an activity at or only at the weekend; (hence) doing something purely for pleasure, or in an amateur or casual way…