IPA: /truːp/
KK: /trup/
To gather or move together in large groups or crowds.
The children began to troop into the auditorium for the show.
Past: trooped
Past Participle: trooped
A group of soldiers or a large number of people, animals, or things.
The troop of soldiers marched in formation during the parade.
Troop originates from Old French *troupe* (meaning a group or crowd), which in turn comes from the Latin *troppus* (meaning a crowd or throng). The word 'troop' refers to a group of people, especially soldiers, gathered together.
Think of a 'crowd' ('troupe') of people coming together, which helps you remember that 'troop' means a group, particularly in a military context.