flint-hearted

from The Collaborative International Dictionary of English v.0.48

Flint-hearted \Flint"-heart`ed\, a.
   Hard-hearted. --Shak.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

18 Moby Thesaurus words for "flinthearted":
      callous, calloused, cold, cold of heart, coldblooded, coldhearted,
      hard, hard of heart, hardened, hardhearted, heartless, insensitive,
      obdurate, stonyhearted, unfeeling, unmerciful, unnatural,
      unresponsive