The Collaborative International Dictionary of English v.0.48:

Exigible \Ex"i*gi*ble\, a. [Cf. F. exigible. See Exigent.]
   That may be exacted; repairable. [R.] --A. Smith.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

EXIGIBLE. That which may be exacted demandable; requirable.