Source : Webster's Revised Unabridged Dictionary (1913)

Accessibility \Ac*cess`i*bil"i*ty\, n. [L. accessibilitas: cf.
   F. accessibilit['e].]
   The quality of being accessible, or of admitting approach;
   receptibility. --Langhorne.

Source : WordNet®

accessibility
     n 1: the quality of being at hand when needed [syn: {handiness},
          {availability}, {availableness}] [ant: {inaccessibility},
           {inaccessibility}]
     2: the attribute of being easy to meet or deal with [syn: {approachability}]
        [ant: {unapproachability}]