Source : Webster's Revised Unabridged Dictionary (1913)

Endolymph \En"do*lymph\, n. [Endo- + lymph: cf. F. endolymphe.]
   (Anat.)
   The watery fluid contained in the membranous labyrinth of the
   internal ear.

Source : WordNet®

endolymph
     n : the bodily fluid that fills the membranous labyrinth of the
         inner ear