Source : Webster's Revised Unabridged Dictionary (1913)

Considerable \Con*sid"er*a*ble\, a. [Cf. F. consid['e]rable.]
   1. Worthy of consideration, borne in mind, or attended to.

            It is considerable, that some urns have had
            inscriptions on them expressing that the lamps were
            burning.                              --Bp. Wilkins.

            Eternity is infinitely the most considerable
            duration.                             --Tillotson.

   2. Of some distinction; noteworthy; influential; respectable;
      -- said of persons.

            You are, indeed, a very considerable man. --Junius.

   3. Of importance or value.

            In painting, not every action, nor every person, is
            considerable enough to enter into the cloth.
                                                  --Dryden.

            A considerable sum of money.          --Prescott.

Source : WordNet®

considerable
     adj : large or relatively large in number or amount or extent or
           degree; "a considerable quantity"; "the economy was a
           considerable issue in the campaign"; "went to
           considerable trouble for us"; "spent a considerable
           amount of time on the problem" [ant: {inconsiderable}]