rock-ribbed vs rockbound

rock-ribbed and rockbound both are adjectives.

Word	Noun	Adjective	Verb	Adverb
rock-ribbed	No	Yes	No	No
rockbound	No	Yes	No	No

As adjectives, rock-ribbed and rockbound are synonyms defined as:

rock-ribbed and rockbound: abounding in or bordered by rocky cliffs or scarps

rock-ribbed (adjective)	rockbound (adjective)
tradition-bound and obstinately opinionated	abounding in or bordered by rocky cliffs or scarps
abounding in or bordered by rocky cliffs or scarps