noun
advance unit; special mission unit
Military term for a unit sent ahead of the main force on a special mission, such as reconnaissance or a raid.
挺進隊が敵陣の偵察に向かった。
The advance unit went to scout the enemy position.
挺進 (ていしん, 'advance boldly') + 隊 (たい, 'unit, corps'). The term is associated with Japanese military terminology, particularly from the World War II era.