Medium
From Tardis Wiki, the free Doctor Who reference
A medium was an individual who could contact the spirits of the dead, or one who pretended to be able to do so. (PROSE: Scared Stiff)
Gwyneth acted as a medium between humans and the Gelth. The Ninth Doctor commented that he "love[d] a happy medium", much to the amusement of Rose Tyler. (TV: The Unquiet Dead)
