Meaning

• (collective) A collection of people; a number; a multitude (in general).

• A small unit of cavalry or armour commanded by a captain, corresponding to a platoon or company of infantry.

• A detachment of soldiers or police, especially horse artillery, armour, or state troopers.

• Soldiers, military forces (usually "troops").

• A company of stageplayers; a troupe.

• A basic unit of girl or boy scouts, consisting of 6 to 10 youngsters.

• (collective) A group of baboons.

• A particular roll of the drum; a quick march.

• Mushrooms that are in a close group but not close enough to be called a cluster.

Meaning

• To move in numbers; to come or gather in crowds or troops.

• To march on; to go forward in haste.

• To move or march as if in a crowd.

  "The children trooped into the room."