a body of citizens enrolled for military service, and called out periodically for drill but serving full time only in emergencies.
2.
a body of citizen soldiers as distinguished from professional soldiers.
3.
all able-bodied males considered by law eligible for military service.
4.
a body of citizens organized in a paramilitary group and typically regarding themselves as defenders of individual rights against the presumed interference of the federal government.
Origin: 1580–90; < Latinmīlitia soldiery, equivalent to mīlit- (stem of mīles) soldier + -ia-ia
1590, "system of military discipline," from L. militia "military service, warfare," from miles "soldier" (see military). Sense of "citizen army" (as distinct from professional soldiers) is first recorded 1696, perhaps from Fr. milice. In U.S. history, "the whole body of
men declared by law amenable to military service, without enlistment, whether armed and drilled or not" (1777).