To collect or gather (something) together.
- The city hall needs to round up all the wrongly parked bikes across the city.
- They rounded up a group of experts and got their opinions.
- In the autumn we round up all the hill sheep and bring them down into the barn.
- During the Holocaust, the Nazis rounded up Jews into ghettos and concentration camps.
- Major Strasser has been shot. Round up the usual suspects.
To gather (livestock such as cattle, sheep, geese, etc.) together, such as by encircling them.
- In the autumn we round up all the hill sheep and bring them down into the barn.
To arrest or detain a group of people based on collective (rather than individualized) cause or suspicion, often as a form of targeted persecution.
- During the Holocaust, the Nazis rounded up Jews into ghettos and concentration camps.
- Major Strasser has been shot. Round up the usual suspects.
To round (a number) to the smallest integer that is not less than it, or to some other greater value, especially a whole number of hundreds, thousands, etc.
- The total is $24,995 — let's round it up to $25,000.