incapable

adj

1. Not capable (of doing something); unable.

   “A pint glass is incapable of holding more than a pint of liquid.”

   “I consider him incapable of dishonesty.”

   “The British people seem incapable of avoiding the habit of leaving litter wherever they go, and the railways certainly seem to receive their fair share of it, in carriages and on stations.”

   “According to the prevailing Danish rationale, Greenlanders were naïve and childlike, in need of protection and incapable of governing themselves.”

2. Not in a state to receive; not receptive; not susceptible; not able to admit.

   “incapable of pain, or pleasure; incapable of stain or injury”

noun

1. (dated)One who is morally or mentally weak or inefficient; an imbecile; a simpleton.