Source : Webster's Revised Unabridged Dictionary (1913)

Inseparable \In*sep"a*ra*ble\, a. [L. inseparabilis: cf. F.
   ins['e]parable. See {In-}, and {Separable}.]
   1. Not separable; incapable of being separated or disjoined.

            The history of every language is inseparable from
            that of the people by whom it is spoken. --Mure.

            Liberty and union, now and forever, one and
            inseparable.                          --D. Webster.

   2. (Gram.) Invariably attached to some word, stem, or root;
      as, the inseparable particle un-.

Source : WordNet®

inseparable
     adj : not capable of being separated; "inseparable pieces of rock"