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

But he was diagnosed in May 2025 with normal pressure hydrocephalus, which is a condition in which cerebrospinal fluid builds up inside the skull and presses on the brain, according to the Cleveland Clinic. — Corky Siemaszko, NBC news, 10 Sep. 2026

The 77-year-old musician revealed in May 2025 that he had been diagnosed with normal pressure hydrocephalus, in which cerebrospinal fluid builds up inside the skull and presses on the brain. — Pat Saperstein, Variety, 9 Sep. 2026

The family's attorney, Robert Glassman, said the little 4-year-old boy is nonverbal, has autism, spina bifida and hydrocephalus. — CBS News, 10 Apr. 2026

The mother told police about the boy's long medical history, including being diagnosed with cerebral palsy, hip dysplasia and hydrocephalus. — Jade Jackson, IndyStar, 27 Mar. 2026

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