1Troops specially trained and equipped for carrying out sudden assaults, especially against enemy strongholds; specifically those of the German army during the First World War (1914–18). Compare shock troop , "assault troops". Now chiefly historical.
2In extended use and figurative. The driving force of an activity or movement; a group leading a vigorous challenge or defence.
3historical The troops of the Sturmabteilung, the paramilitary wing of the Nazi party. Compare "storm trooper".
4In singular A detachment of such troops.
Early 20th century; earliest use found in The Times. From storm + troop, after German Sturmtruppe.