MC meaning in Military and Defence ?

Marines, or naval infantry, are typically a military force trained to operate in littoral zones in support of naval operations. Historically, tasks undertaken by marines have included helping maintain discipline and order aboard the ship (reflecting the pressed nature of the ships' company and the risk of mutiny), the boarding of vessels during combat or capture of prize ships, and providing manpower for raiding ashore in support of the naval objectives. In most countries, the marines are an integral part of that state's navy.

The exact term "marine" does not exist in many other languages. In French-speaking countries, two terms exist which could be translated as "marine", but do not translate exactly: troupes de marine and fusiliers-marins; similar pseudo-translations exist elsewhere, e.g. Fuzileiros Navais in Portuguese. The word marine means Navy in many European languages such as French, German, Dutch and Norwegian.