A body of men; esp., an organized division of the military establishment; as, the marine corps; the corps of topographical engineers; specifically, an army corps.
A component of the army forming a tactical unit comprised of a number of divisions
In the military the term "corps" has both a general and specific meaning. In general it refers to a group of men and women who share similar functions such as the Medical Corps or the Signal Corps. In its specific sense, the word designates an organizational unit subordinate to a field army composed of two or more divisions.