1.
If the police or army round up a number of people, they arrest or capture them.
The police rounded up a number of suspects...
She says the patrolmen rounded them up at the village school and beat them with rifle butts.
PHRASAL VERB : V P n (not pron) , V n P
2.
If you round up animals or things, you gather them together.
He had sought work as a cowboy, rounding up cattle...
PHRASAL VERB : V P n (not pron)
3.
see also round 2, roundup