Unable

1. a. 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; as, unable for work; unable to bear fatigue.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.