different between uncastable vs uncashable

English

un- +? castable

uncastable (comparative more uncastable, superlative most uncastable)

That cannot be cast (filled with, or allocated, a theatrical role).
- 1974, New York Magazine (volume 7, number 3, 21 January 1974)
  Colleen Dewhurst, though in many ways wrong for the virtually uncastable Josie, is as lucid and luminous...
(computing, programming) That cannot be cast (converted to other data types).
- 2000, Larry Wall, Tom Christiansen, Jon Orwant, Programming Perl
  They're strongly typed, uncastable pointers...
(medicine) That cannot be set in a cast.
- 2005, Mercer Rang, Maya E Pring, Dennis Ray Wenger, Rang's children's fractures
  ...internal fixation in children with open, unstable, or otherwise uncastable forearm fractures...
That cannot be used for, or produced through, casting (manufacturing with a mould).
- 1943, The Mining Magazine
  Casting must be done within a day or two of moulding or the moulds will begin to wind-dry and become uncastable...
- 1982, Production engineering
  This allows the casting of otherwise uncastable materials, with acceptable rejection rates, and can increase ductility by as much as a factor of six.