1.Definition: (especially used in traditional Hindu belief of the lowest caste or castes) defiling
2.Definition: beyond the reach of criticism or attack or impeachment
"For the first time criticism was directed at a hitherto untouchable target"
3.Definition: forbidden to the touch
"In most museums such articles are untouchable"
4.Definition: impossible to assail
5.Definition: not capable of being obtained
"Untouchable resources buried deep within the earth"