In a more general sense, 'abroad' means that something moves or spreads in many directions outside a certain place.
News spread abroad quickly.
Rumors flew abroad in town.
Figuratively, 'abroad' means that something is talked about openly or is well known among people, not hidden.
His name was abroad after the scandal.
The secret was abroad in the office.
In older or poetic English, 'abroad' can mean being out on the sea or on water, away from land.
The ship ventured abroad on the ocean.
Fishermen went abroad early in the morning.
