Synonyms for Unable:

adj.

helpless (adjective)
helpless, impotent.
not having talent, skill (adjective)
inefficacious, unskilled, Impuissant, powerless, not able, inept, incompetent, unqualified, impotent, inadequate, weak, unfitted, helpless, inoperative, unfit, incapacitated.
untrained (adjective)
unskilled.

n.

incompetent, unqualified, ability, unfit. incapable (noun)
inefficacious, inadequate, weak, not able, powerless, incompetent, incapacitated, Impuissant, inoperative, inept, impotent, unqualified, helpless, unskilled, unfitted.

Other synonyms:

unqualified. dependent
helpless.
incapable
incompetent.
incompetent
unfit.
Other relevant words:
inefficacious, Impuissant, inadequate, unskilled, ability, not able, powerless, incapacitated, incompetent, unfitted, inoperative, unqualified, unfit, inept, helpless, weak, impotent.

Usage examples for unable

  1. " How very strange it is," she replied after a moment's consideration, " that I should be perfectly unable to say whether he did or did not! – The Vicar of Wrexhill by Mrs [Frances] Trollope
  2. One of the overturned chairs, however, had struck him in the stomach, and this had rather knocked his breath out, which made him unable to talk for a little while. – Bunny Brown and His Sister Sue Keeping Store by Laura Lee Hope
  3. Finding himself unable to answer the question, he at once set plans for reaching that land. – The Blue Envelope by Roy J. Snell