Source : Webster's Revised Unabridged Dictionary (1913)

Exhaustible \Ex*haust"i*ble\, a.
   Capable of being exhausted, drained off, or expended.
   --Johnson.

Source : WordNet®

exhaustible
     adj 1: capable of being used up [ant: {inexhaustible}]
     2: capable of being used up; capable of being exhausted; "our
        exhaustible reserves of fossil fuel"