changeable has 7 distinct synonyms spread across 4 of its 4 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 unchangeable.
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.
such that alteration is possible; having a marked tendency to change
“changeable behavior”
Synonyms, antonyms and the broader and narrower relations for changeable come from Princeton University’s WordNet. Full sources and licences.
varying in color when seen in different lights or from different angles
“changeable taffeta”