WordNet sense 1 (unaware of or indifferent to):

unaffected

WordNet sense 2 (deficient in human sensibility; not mentally or morally sensitive):

insensitive

WordNet sense 3 (lacking sensation):

benumbed, numb

WordNet sense 4 (barely able to be perceived):

indiscernible, undetectable

WordNet sense 5 (impossible or difficult to perceive by the mind or senses):

imperceptible, unperceivable

WordNet sense 6 (unresponsive to stimulation):

senseless

WordNet sense 7 (not conscious; lacking awareness and the capacity for sensory perception as if asleep or dead):

unconscious