Source : Webster's Revised Unabridged Dictionary (1913)

Demonstrable \De*mon"stra*ble\, a. [L. demonstrabilis: cf. OF.
   demonstrable, F. d['e]montrable.]
   1. Capable of being demonstrated; that can be proved beyond
      doubt or question.

            The grand articles of our belief are as demonstrable
            as geometry.                          --Glanvill.

   2. Proved; apparent. [Obs.] --Shak.

Source : WordNet®

demonstrable
     adj 1: necessarily or demonstrably true; "demonstrable truths"
            [syn: {incontrovertible}]
     2: capable of being demonstrated or proved; "obvious lies"; "a
        demonstrable lack of concern for the general welfare";
        "practical truth provable to all men"- Walter Bagehot
        [syn: {provable}]