philosophy has 4 distinct synonyms spread across 1 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 belief (or system of beliefs) accepted as authoritative by some group or school
the rational investigation of questions about existence and knowledge and ethics
any personal belief about how to live or how to deal with a situation
“self-indulgence was his only philosophy”
Synonyms, antonyms and the broader and narrower relations for philosophy come from Princeton University’s WordNet. Full sources and licences.