convertible has 6 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 inconvertible.
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 car that has top that can be folded or removed
a corporate security (usually bonds or preferred stock) that can be exchanged for another form of security (usually common stock)
a sofa that can be converted into a bed
capable of being exchanged for or replaced by something of equal value
“convertible securities”
capable of being changed in substance as if by alchemy
“is lead really transmutable into gold?”
1 of the 6 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for convertible.
Synonyms, antonyms and the broader and narrower relations for convertible come from Princeton University’s WordNet. Full sources and licences.