[1] : The Collaborative International Dictionary of English v.0.48

callous \cal"lous\, a. l. callosus callous hard, fr. callum,
   callus, callous skin: cf. f. calleux.
   1. hardened; indurated. "a callous hand." --goldsmith. "a
      callous ulcer." --dunglison.
      1913 webster

   2. hardened in mind; insensible; unfeeling; unsusceptible.
      "the callous diplomatist." --macaulay.
      1913 webster

            it is an immense blessing to be perfectly callous to
            ridicule.                             --t. arnold.

   syn: obdurate; hard; hardened; indurated; insensible;
        unfeeling; unsusceptible. see obdurate. --
        cal"lously, adv.
        1913 webster

              a callousness and numbness of soul. --bentley.
        1913 webster
see also:
obdurate cal"lously 

[2] : WordNet (r) 2.0

callously
     adv : in a callous way; "he callously exploited their feelings"
           syn: unfeelingly
see also:
unfeelingly 

Callously >> C Words
Callously, definition of term: Callously
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