Insensible

a.
  1. Destitute of the power of feeling or perceiving; wanting bodily sensibility; unconscious.
  2. Not susceptible of emotion or passion; void of feeling; apathetic; unconcerned; indifferent; as, insensible to danger, fear, love, etc.; -- often used with of or to.
  3. Incapable of being perceived by the senses; imperceptible. Hence: Progressing by imperceptible degrees; slow; gradual; as, insensible motion.
  4. Not sensible or reasonable; meaningless.
  5. Incapable of feeling a specific sensation or emotion; as, insensible to pity.