Source : Webster's Revised Unabridged Dictionary (1913)

Pitiless \Pit"i*less\, a.
   1. Destitute of pity; hard-hearted; merciless; as, a
      pitilessmaster; pitiless elements.

   2. Exciting no pity; as, a pitiless condition. --
      {Pit"i*less*ly}, adv. -- {Pit"i*less*ness}, n.

Source : WordNet®

pitiless
     adj 1: without mercy or pity; "an act of ruthless ferocity"; "a
            monster of remorseless cruelty" [syn: {remorseless}, {ruthless},
             {unpitying}]
     2: deficient in humane and kindly feelings [syn: {unkind}]