rough water vs roughness

rough water and roughness both are nouns.

Word	Noun	Adjective	Verb	Adverb
rough water	Yes	No	No	No
roughness	Yes	No	No	No

As nouns, rough water and roughness are synonyms defined as:

rough water and roughness: used of the sea during inclement or stormy weather

Other synonyms of rough water include choppiness.

rough water (noun)	roughness (noun)
used of the sea during inclement or stormy weather	harsh or severe speech or behavior
	a texture of a surface or edge that is not smooth but is irregular and uneven
	the quality of being harsh or rough or grating to the senses
	an unpolished unrefined quality
	the formation of small pits in a surface as a consequence of corrosion
	used of the sea during inclement or stormy weather
	rowdy behavior