ordinary has 2 distinct synonyms spread across 2 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 extraordinary.
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 expected or commonplace condition or situation
“not out of the ordinary”
a clergyman appointed to prepare condemned prisoners for death
an early bicycle with a very large front wheel and small back wheel
(heraldry) any of several conventional figures used on shields
not exceptional in any way especially in quality or ability or size or degree
“ordinary everyday objects”
Synonyms, antonyms and the broader and narrower relations for ordinary come from Princeton University’s WordNet. Full sources and licences.