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

Joel, 76, has been in the news lately after revealing that he’s been diagnosed with the brain disorder normal pressure hydrocephalus, or NPH, leading him to cancel tour dates while he is being treated for the disease. —Tim Lammers, Forbes.com, 24 June 2025

Billy Joel diagnosed with NPH Normal pressure hydrocephalus, or NPH, is a disorder in which excess fluid accumulates in the brain, causing issues with thinking and reasoning as well as sometimes walking and bladder control, according to the Alzheimer's Association. —Anna Kaufman, USA Today, 26 Apr. 2025

Joel announced in May that he’d been diagnosed with normal pressure hydrocephalus (NPH), a treatable brain condition that can affect hearing, vision and balance. —Rachel Desantis, People.com, 21 July 2025

The earlier normal pressure hydrocephalus is caught and treated, the better. —Sydney Lupkin, NPR, 24 May 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