restriction has 2 distinct synonyms spread across 3 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.
a principle that limits the extent of something
“I am willing to accept certain restrictions on my movements”
an act of limiting or restricting (as by regulation)
Synonyms, antonyms and the broader and narrower relations for restriction come from Princeton University’s WordNet. Full sources and licences.
the act of keeping something within specified bounds (by force if necessary)
“the restriction of the infection to a focal area”