If people troop somewhere, they walk there in a group, often in a sad or tired way. They all trooped back to the house for a rest. if a group of people troop somewhere, they walk there together in a way that shows they are tired or bored troop off/along/out etc
A troop is a group of soldiers within a cavalry or armoured regiment. a troop of enemy cavalry trotting towards the Dutch right flank
Specifically, a small body of cavalry, light horse, or dragoons, consisting usually of about sixty men, commanded by a captain; the unit of formation of cavalry, corresponding to the company in infantry
a group of soldiers a cavalry unit corresponding to an infantry company an orderly crowd; "a troop of children" a unit of girl or boy scouts move or march as if in a crowd; "They children trooped into the room