cadre

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

• noun A nucleus of trained personnel around which a larger organization can be built and trained.
• noun A tightly knit group of zealots who are active in advancing the interests of a revolutionary party.
• noun A member of such a group.

from The Century Dictionary.

• noun A skeleton or framework; specifically, in France, the permanently organized skeleton or framework of a regiment or corps, consisting of the commissioned and non-commissioned officers, musicians, artificers, etc., around whom the rank and file may be assembled at short notice.

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

• noun (Mil.) The framework or skeleton upon which a regiment is to be formed; the officers of a regiment forming the staff.

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

• noun A frame or framework.
• noun military The framework or skeleton upon which a new regiment is to be formed; the officers of a regiment forming the staff.
• noun The core of a managing group, or a member of such a group.

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

• noun a nucleus of military personnel capable of expansion
• noun a small unit serving as part of or as the nucleus of a larger political movement