A marauder is defined In the law to be one who, while employed m the army as a soldier, commits larceny or robbery in the neighborhood of the camp, or while wandering away from the army. But in the modern and metaphorical sense of the word, as now sometimes used in common speech, it seems to be applied to a class of persons who are not a part of any regular army, and are not answerable to any military discipline, but who are mere lawless banditti, engaged in plundering, robbery, murder, and all conceivable crimes.
MARAUDER
TheLaw.com Law Dictionary & Black's Law Dictionary 2nd Ed.