hydrocephalus

noun

hy·​dro·​ceph·​a·​lus ˌhī-drō-ˈse-fə-ləs 

variants or less commonly hydrocephaly

ˌhī-drō-ˈse-fə-lē 

: an abnormal increase in the amount of cerebrospinal fluid within the cranial cavity (as from obstructed flow, excess production, or defective absorption) that is accompanied by expansion of the cerebral ventricles and often increased intracranial pressure, skull enlargement, and cognitive decline

Examples of hydrocephalus in a Sentence

Recent Examples on the Web

The musician, 76, explained that he was diagnosed with normal pressure hydrocephalus, and underwent corrective shunt brain surgery last week. —Rachel Desantis, PEOPLE, 25 Nov. 2025

The Duke of Sussex was photographed having a sword fight with balloons with 9-year-old Gwen Foster, a girl born with spina bifida and hydrocephalus. —Simon Perry, People.com, 8 Sep. 2025

Normal pressure hydrocephalus is a condition in which cerebrospinal fluid builds up inside of the skull and presses on the brain, according to Cleveland Clinic. —Anna Kaplan, NBC news, 22 July 2025

On May 23, Joel canceled all of his upcoming concerts after he was diagnosed with normal pressure hydrocephalus, a brain disorder. —Brendan Morrow, USA Today, 5 June 2025

Word History

Etymology

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

First Known Use

1670, in the meaning defined above

Kids Definition

hydrocephalus

noun

hy·​dro·​ceph·​a·​lus ˌhī-drō-ˈsef-ə-ləs 

variants also hydrocephaly

-ˈsef-ə-lē 

: an abnormal condition in which an increased amount of cerebrospinal fluid causes an increase in the size of the ventricles of the brain and the size of the skull and the wasting away of the brain

Medical Definition

hydrocephalus

noun

hy·​dro·​ceph·​a·​lus -ˈsef-ə-ləs, British also -ˈkef- 

plural hydrocephali -ˌlī 

: an abnormal increase in the amount of cerebrospinal fluid within the cranial cavity (as from obstructed flow, excess production, or defective absorption) that is accompanied by expansion of the cerebral ventricles and often increased intracranial pressure, skull enlargement, and cognitive decline