Source : Webster's Revised Unabridged Dictionary (1913)

Defensible \De*fen"si*ble\, a. [Cf. F. d['e]fensable, LL.
   defensabilis, defensibilis. See {Defense}, and cf.
   {Defendable}.]
   1. Capable of being defended; as, a defensible city, or a
      defensible cause.

   2. Capable of offering defense. [Obs.] --Shak.

Source : WordNet®

defensible
     adj : capable of being defended [syn: {defendable}]