Source : Webster's Revised Unabridged Dictionary (1913)

Imprescriptible \Im`pre*scrip"ti*ble\, a. [Pref. im- not +
   prescriptible: cf. F. imprescriptible.]
   1. Not capable of being lost or impaired by neglect, by
      disuse, or by the claims of another founded on
      prescription.

            The right of navigation, fishing, and others that
            may be exercised on the sea, belonging to the right
            of mere ability, are imprescriptible. --Vattel
                                                  (Trans. )

   2. Not derived from, or dependent on, external authority;
      self-evidencing; obvious.

            The imprescriptible laws of the pure reason.
                                                  --Colerridge.