/huy'dreuh sef"euh leuhs/ , n. Pathol.
an accumulation of serous fluid within the cranium, esp. in infancy, due to obstruction of the movement of cerebrospinal fluid, often causing great enlargement of the head; water on the brain.
Also, hydrocephaly /huy'dreuh sef"euh lee/ .
[ 1660-70; hydrocephalus ( morbus ) water-headed (sickness), trans. of Gk tò hydroképhalon ( páthos ). See HYDRO- 1 , -CEPHALOUS ]