also round-up, by 1869 in the cattle drive sense; from verbal phrase round up "to collect in a mass" (1610s; specifically of livestock from 1847); see round (v.) + up (adv.). Meaning "summary of news items" is recorded from 1886.
a mass roundup of suspects
rounder
Roundhead
roundhouse
roundness
round-table
roundup
rouse
rouser
roust
roustabout
rout