Source : Webster's Revised Unabridged Dictionary (1913)

Expressible \Ex*press"i*ble\ (-[i^]*b'l), a.
   Capable of being expressed, squeezed out, shown, represented,
   or uttered. -- {Express"i*bly},adv.

Source : WordNet®

expressible
     adj : capable of being expressed; "an expressible emotion" [ant: {inexpressible}]