Source : Webster's Revised Unabridged Dictionary (1913)

Insensitive \In*sen"si*tive\, a.
   Not sensitive; wanting sensation, or wanting acute
   sensibility. --Tillotson. Ruskin.

Source : WordNet®

insensitive
     adj 1: not responsive to physical stimuli; "insensitive to
            radiation" [ant: {sensitive}]
     2: deficient in human sensibility; not mentally or morally
        sensitive; "insensitive to the needs of the patients"
        [ant: {sensitive}]