formality has 2 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. Its one recorded opposite is informality.
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 manner that strictly observes all forms and ceremonies
“the formality of his voice made the others pay him close attention”
Synonyms, antonyms and the broader and narrower relations for formality come from Princeton University’s WordNet. Full sources and licences.
compliance with formal rules
“courtroom formality”