Sgt in AM, use Sgt. Sgt is the written abbreviation for Sergeant when it is used as a title. Sgt Johnston. sergeant. the written abbreviation of sergeant
{i} noncommissioned military officer ranking above a corporal or airman first class; police office ranking below a captain or lieutenant
noncommissioned officer serving as chief administrative assistant in a military headquarters (USA); noncommissioned officer of the highest rank (Britain)