restraint has 5 distinct synonyms spread across 4 of its 6 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 unrestraint.
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.
the act of controlling by restraining someone or something
“the unlawful restraint of trade”
discipline in personal and social activities
“he was a model of polite restraint”
the state of being physically constrained
“dogs should be kept under restraint”
a rule or condition that limits freedom
“legal restraints”
lack of ornamentation
“the room was simply decorated with great restraint”
Synonyms, antonyms and the broader and narrower relations for restraint come from Princeton University’s WordNet. Full sources and licences.