The Collaborative International Dictionary of English v.0.48:

coldhearted \cold"heart`ed\, cold-hearted \cold"-heart`ed\, a.
   Wanting passion or feeling or emotional warmth; indifferent.
   -- cold"-heart`ed*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

coldhearted
    adj 1: lacking in sympathy or feeling [ant: warmhearted]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "cold-hearted":
   apathetic, callous, cold, cool, cruel, frigid, heartless,
   indifferent, insensitive, mean, merciless, pitiless, ruthless,
   thick-skinned, thoughtless, uncaring, uncharitable, unfeeling,
   unkind, unmerciful, unsympathetic, unthoughtful



Moby Thesaurus II by Grady Ward, 1.0:

64 Moby Thesaurus words for "coldhearted":
   affectless, anesthetized, arctic, autistic, blunt, callous,
   calloused, catatonic, chill, chilly, cold, cold as charity,
   cold of heart, cold-blooded, coldblooded, cool, dispassionate,
   drugged, dull, emotionally dead, emotionless, flinthearted, frigid,
   frosted, frosty, frozen, hard, hard of heart, hardened,
   hardhearted, heartless, icy, immovable, impassible, impassive,
   inexcitable, insensitive, insusceptible, ironhearted, nonemotional,
   obdurate, objective, obtuse, out of touch, passionless,
   self-absorbed, soulless, spiritless, stonyhearted, unaffectionate,
   uncompassionate, unemotional, unfeeling, unimpassioned,
   unimpressionable, unloving, unmerciful, unnatural, unpassionate,
   unresponding, unresponsive, unsusceptible, unsympathetic,
   untouchable