Source : Webster's Revised Unabridged Dictionary (1913)

Indissoluble \In*dis"so*lu*ble\, a. [L. indissolubilis: cf. F.
   indissoluble. See {In-} not, and {Dissoluble}, and cf.
   {Indissolvable}.]
   1. Not dissoluble; not capable of being dissolved, melted, or
      liquefied; insoluble; as few substances are indissoluble
      by heat, but many are indissoluble in water. --Boyle.

   2. Incapable of being rightfully broken or dissolved;
      perpetually binding or obligatory; firm; stable, as, an
      indissoluble league or covenant.

            To the which my duties Are with a most indissoluble
            tie Forever knit.                     --Shak.

Source : WordNet®

indissoluble
     adj 1: not soluble
     2: used of decisions and contracts