noun
( plural sergeants major or sergeant majors )
1. obsolete : a regimental field officer serving either as a major or adjutant
2. obsolete : a general officer commanding large bodies of troops
3.
a. : a noncommissioned officer in the marine corps ranking above a first sergeant — see rank table
b. : a noncommissioned officer in the army, air force, or marine corps serving as chief administrative assistant in a headquarters
4.
a. : a small deep-bodied compressed damselfish ( Abudefduf marginatus ) bluish green to yellow with black vertical stripes on the sides that is widely distributed in warm seas on both coasts of the Americas
b. : a related fish ( A. saxatilis ) of the western tropical Atlantic
5. : the chief local officer in a Salvation Army corps who assists the corps officer