Main entry: inconvertible, unconvertible, unexchangeable
Definition: used especially of currencies; incapable of being exchanged for or replaced by another currency of equal value
Antonyms: exchangeable, convertible
Definition: capable of being exchanged for or replaced by something of equal value
Main entry: inconvertible, untransmutable
Definition: not capable of being changed into something else
Usage: the alchemists were unable to accept the inconvertible nature of elemental metals
Antonyms: commutable
Definition: subject to alteration or change