violence has 7 distinct synonyms spread across 2 of its 3 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. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
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.
an act of aggression (as one against a person who resists)
“he may accomplish by craft in the long run what he cannot do by force and violence in the short one”
the property of being wild or turbulent
“the storm's violence”
a turbulent state resulting in injuries and destruction etc.
Synonyms, antonyms and the broader and narrower relations for violence come from Princeton University’s WordNet. Full sources and licences.