sergeant first class

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

• noun A noncommissioned rank in the US Army that is above staff sergeant and below master sergeant.
• noun One who holds this rank.

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

• noun US, Army A non-commissioned officer in the United States Army, ranking above a staff sergeant and below a master sergeant or first sergeant.

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

• noun a sergeant in the Army above the rank of staff sergeant and below master sergeant