Definify.com

Webster 1828 Edition

Adj.

Not malleable; not capable of being hammered into a plate, or of being extended by beating.

unmalleable ‎(comparative more unmalleable, superlative most unmalleable)

Not malleable.
- 2007 June 5, Dave Kehr, “New DVDs: Dean Martin and Jerry Lewis”, in New York Times:
  If location photography meant better-looking backgrounds than the painted flats or rear-projection screens of the studios, it also meant that filmmakers had to curtail their creative urges in the face of unmalleable reality.