from The American Heritage® Dictionary of the English Language, 5th Edition.

  • adjective Lacking the necessary power, authority, or means; not able; incapable.
  • adjective Lacking mental or physical capability or efficiency; incompetent.
  • adjective Usage Problem Not susceptible to action or treatment.

from The Century Dictionary.

  • Not able.
  • Lacking in ability; incapable.
  • Weak; helpless; useless.

from the GNU version of the Collaborative International Dictionary of English.

  • adjective Not able; not having sufficient strength, means, knowledge, skill, or the like; impotent; weak; helpless; incapable; -- now usually followed by an infinitive or an adverbial phrase.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • adjective Not able; lacking a certain ability.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adjective (usually followed by `to') not having the necessary means or skill or know-how
  • adjective lacking in power or forcefulness
  • adjective (usually followed by `to') lacking necessary physical or mental ability


from Wiktionary, Creative Commons Attribution/Share-Alike License

un- +‎ able


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