Source : Webster's Revised Unabridged Dictionary (1913)

Intracellular \In`tra*cel"lu*lar\, a. (Biol.)
   Within a cell; as, the intracellular movements seen in the
   pigment cells, the salivary cells, and in the protoplasm of
   some vegetable cells.

Source : WordNet®

intracellular
     adj : located or occurring within a cell or cells; "intracellular
           fluid" [ant: {extracellular}]