capableness

from WordNet (r) 3.0 (2006)

capableness
    n 1: an aptitude that may be developed [syn: {capability},
         {capableness}, {potentiality}] [ant: {incapability},
         {incapableness}]
    2: the quality of being capable -- physically or intellectually
       or legally; "he worked to the limits of his capability" [syn:
       {capability}, {capableness}] [ant: {incapability},
       {incapableness}]

from The Collaborative International Dictionary of English v.0.48

Capableness \Ca"pa*ble*ness\, n.
   The quality or state of being capable; capability;
   adequateness; competency.
   [1913 Webster]