Source : Webster's Revised Unabridged Dictionary (1913)

Unfeeling \Un*feel"ing\, a.
   1. Destitute of feeling; void of sensibility; insensible;
      insensate.

   2. Without kind feelings; cruel; hard-hearted.

            To each his sufferings: all are men, Condemned alike
            to groan; The tender for another's pain, Th'
            unfeeling for his own.                --Gray.
      -- {Un*feel"ing*ly}, adv. -- {Un*feel"ing*ness}, n.

Source : WordNet®

unfeelingly
     adv 1: without compassionate feelings; "unfeelingly, she required
            her maid to work on Christmas Day" [ant: {feelingly}]
     2: in a callous way; "he callously exploited their feelings"
        [syn: {callously}]