bull has 20 distinct synonyms spread across 9 of its 15 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 bear.
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 serious and ludicrous blunder
“he made a bad bull of the assignment”
the second sign of the zodiac; the sun is in this sign from about April 20 to May 20
a formal proclamation issued by the pope (usually written in antiquated characters and sealed with a leaden bulla)
mature male of various mammals of which the female is called `cow'; e.g. whales or elephants or especially cattle
Synonyms, antonyms and the broader and narrower relations for bull come from Princeton University’s WordNet. Full sources and licences.