roughness has 10 distinct synonyms spread across 6 of its 7 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is smoothness.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
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 crudeness of frontier dwellings depressed her”
used of the sea during inclement or stormy weather
the formation of small pits in a surface as a consequence of corrosion
harsh or severe speech or behavior
“men associate the roughness of nonstandard working-class speech with masculinity”
Synonyms, antonyms and the broader and narrower relations for roughness come from Princeton University’s WordNet. Full sources and licences.