Source : Webster's Revised Unabridged Dictionary (1913)

Kephalin \Keph"a*lin\ (k[e^]f"[.a]*l[i^]n), n. [Gr. kefalh` the
   head.] (Physiol. Chem.)
   One of a group of nitrogenous phosphorized principles,
   supposed by Thudichum to exist in brain tissue.