1. Adjective.  resistant to reason; determined; inflexible; unshakeable; unyielding.
  2. Noun.  a rock or mineral held by some to be of impenetrable hardness; a name given to the diamond and other substances of extreme hardness.
  3. Noun.  an embodiment of impregnable hardness.
  4. Noun.  a magnet; a lodestone.

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This entry was last updated on RefTopia from its source on 3/20/2012.