highwayman vs road agent

highwayman and road agent both are nouns.

Word	Noun	Adjective	Verb	Adverb
highwayman	Yes	No	No	No
road agent	Yes	No	No	No

As nouns, highwayman and road agent are synonyms defined as:

highwayman and road agent: a holdup man who stops a vehicle and steals from it

Other synonyms of highwayman include highjacker, hijacker.

highwayman (noun)	road agent (noun)
a holdup man who stops a vehicle and steals from it	a holdup man who stops a vehicle and steals from it