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

In the clip, Prince Harry is seen pretending to fence with Gwen Foster, 9, who was born with spina bifida and hydrocephalus. —Angel Saunders, PEOPLE, 10 Sep. 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

Billy, 76, announced that he had been diagnosed with normal pressure hydrocephalus (NPH) – which affects his vision, hearing and balance -- on social media in May. —Ashley Hume , Larry Fink, FOXNews.com, 24 Aug. 2025

The documentary was completed prior to Joel’s recent diagnosis of normal pressure hydrocephalus, but there are candid assessments of other struggles he’s endured, including depression, bankruptcy and alcoholism. —Melissa Ruggieri, USA Today, 25 July 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