sergeant major

from The American Heritage® Dictionary of the English Language, 4th Edition

• n. Used as a title for a noncommissioned officer serving as chief administrative assistant of a headquarters unit of the U.S. Army or Marine Corps.
• n. One who holds this title.
• n. Chiefly British A noncommissioned or warrant officer of the highest rank in a company or unit of battalion size.
• n. A small damselfish (Abudefduf saxatilis) of warm seas, having a flattened body with dark vertical stripes. Also called cow pilot.

from Wiktionary, Creative Commons Attribution/Share-Alike License

• n. A senior non-commissioned appointment in the Army of a company or unit, directly responsible to the officer in charge for their soliders' performance, standards, discipline, morale, welfare, et al, that can be held by a Warrant Officer or above.
• n. The most senior rank of non-commissioned officer in the United States Army and United States Marine Corps, ranking above a first sergeant.
• n. An appointment (not a rank) in the British Army and Royal Marines, denoting the most senior non-commissioned officer in a battalion, regiment or company.

from the GNU version of the Collaborative International Dictionary of English

• n. The cow pilot.

from The Century Dictionary and Cyclopedia

• n. In the army, the highest non-commissioned officer in a regiment. He acts as assistant to the adjutant.
• n. The cow-pilot, a fish.

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

• n. large blue-grey black-striped damselfish; nearly worldwide
• n. a noncommissioned officer serving as chief administrative officer of a headquarters unit of the Army