cardinal has 10 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 ordinal.
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.
(Roman Catholic Church) one of a group of more than 100 prominent bishops in the Sacred College who advise the Pope and elect new Popes
the number of elements in a mathematical set; denotes a quantity but not the order
crested thick-billed North American finch having bright red plumage in the male
being or denoting a numerical quantity but not order
“cardinal numbers”
Synonyms, antonyms and the broader and narrower relations for cardinal come from Princeton University’s WordNet. Full sources and licences.