Nouns

(n)convertiblea car that has top that can be folded or removed
(n)convertible, convertible securitya corporate security (usually bonds or preferred stock) that can be exchanged for another form of security (usually common stock)
(n)convertible, sofa beda sofa that can be converted into a bed

Adjectives

(a)convertible, exchangeablecapable of being exchanged for or replaced by something of equal value“convertible securities”
(s)convertibledesigned to be changed from one use or form to another“a convertible sofa”, “a convertible coupe”
(s)convertible, transformable, translatable, transmutablecapable of being changed in substance as if by alchemy“is lead really transmutable into gold?”, “ideas translatable into reality”