perilymph

from WordNet (r) 3.0 (2006)

perilymph
    n 1: the bodily fluid that fills the space between the bony
         labyrinth and the membranous labyrinth of the inner ear

from The Collaborative International Dictionary of English v.0.48

Perilymph \Per"i*lymph\, n. (Anat.)
   The fluid which surrounds the membranous labyrinth of the
   internal ear, and separates it from the walls of the chambers
   in which the labyrinth lies.
   [1913 Webster]