sergeant first class

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

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

from Wiktionary, Creative Commons Attribution/Share-Alike License

• n. 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.

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