Main Entry: hy·dro·ceph·a·lus

Pronunciation: \-ˈse-fə-ləs\

Variant(s): also hy·dro·ceph·a·ly \-lē\

Function: noun

Etymology: New Latin hydrocephalus, from Late Latin, hydrocephalic, adjective, from Greek hydrokephalos, from hydr- + kephalē head — more at cephalic

Date: 1670

: an abnormal increase in the amount of cerebrospinal fluid within the cranial cavity that is accompanied by expansion of the cerebral ventricles, enlargement of the skull and especially the forehead, and atrophy of the brain