commando

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A small fighting force specially trained for making quick destructive raids against enemy-held areas.
• noun A member of such a force.
• noun An organized force of Boer troops in South Africa.
• noun A raid made by such a force.
• idiom (go commando) To wear clothing without wearing undergarments, especially underpants.

from The Century Dictionary.

• noun A military expedition or raid undertaken by private individuals for personal ends; more specifically, the name given to the quasimilitary expeditions undertaken by the Boers and English farmers of South Africa against the natives.
• noun The enrolled militia of an electoral district in the late Dutch republics of South Africa.
• noun A unit of the Boer army commanded by an officer whose title was Commandant.

from the GNU version of the Collaborative International Dictionary of English.

• noun In South Africa, a military body or command; also, sometimes, an expedition or raid.
• noun a usually small military unit trained to perform special missions, often behind enemy lines, and usually employing hit-and-run tactics. Such units often have the destruction of fixed targets, such as enemy installations, as their mission, in contrast to normal combat units which engage the enemy army directly.
• noun a member of a commando{2} unit.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A small fighting force specially trained for making quick destructive raids against enemy-held areas
• noun A commando trooper
• noun historical An organized force of Boer troops in South Africa; a raid by such troops

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an amphibious military unit trained for raids into enemy territory
• noun a member of a military unit trained as shock troops for hit-and-run raids