The Collaborative International Dictionary of English v.0.48:

Deceivableness \De*ceiv"a*ble*ness\, n.
   1. Capability of deceiving.
      [1913 Webster]

            With all deceivableness of unrighteousness. --2
                                                  Thess. ii. 10.
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   2. Liability to be deceived or misled; as, the deceivableness
      of a child.
      [1913 Webster]