Source : Webster's Revised Unabridged Dictionary (1913)

Availability \A*vail`a*bil"i*ty\, n.; pl. {Availabilities}.
   1. The quality of being available; availableness.

   Note: The word is sometimes used derogatively in the sense of
         ``mere availableness,'' or capability of success
         without regard to worthiness.

               He was . . . nominated for his availability.
                                                  --Lowell.

   2. That which is available.

Source : WordNet®

availability
     n : the quality of being at hand when needed [syn: {handiness},
         {accessibility}, {availableness}] [ant: {inaccessibility},
          {inaccessibility}]

Source : Free On-Line Dictionary of Computing

availability
     
         The degree to which a system suffers degradation or
        interruption in its service to the customer as a consequence
        of failures of one or more of its parts.
     
        One of the components of {RAS}.
     
        (2000-08-13)