inconvertible
1. [ adjective ] used especially of currencies; incapable of being exchanged for or replaced by another currency of equal value
Synonyms: unexchangeable unconvertible
Related terms: convertible irredeemable convertibility
2. [ adjective ] not capable of being changed into something else
Synonyms: untransmutable
Examples:

"the alchemists were unable to accept the inconvertible nature of elemental metals"

Related terms: incommutable
Similar spelling:   incontestible
  inconvertibility
  inconsiderable
  in_concert
  inconsiderate
  incontinent
  incompatible
  inconvenient
  inconsiderately
  incombustible
  inconvenience
  inconveniently
  incontinence
  inconsolable
  inconsideration
  incongruity
  incompatibly