The Collaborative International Dictionary of English v.0.48:

Inductile \In*duc"tile\, a. [Pref. in- not + ductile: cf. F.
   inductile.]
   Not ductile; incapable of being drawn into threads, as a
   metal; inelastic; tough.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "inductile":
   adamant, adamantine, immovable, immutable, inelastic, inextensible,
   inextensile, inextensional, inflexible, intractable, intractile,
   irresilient, nonelastic, nonstretchable, stubborn, unalterable,
   unbending, unextendible, unextensible, unflexible, ungiving,
   unlimber, unmalleable, unpliable, unpliant, untractable,
   unyielding