Hydrocephalus (pronunciation IPA: /ˌhaɪˌdɹoʊˈsɛfələs/) is a term derived from the Greek words "hydro" meaning water, and "cephalus" meaning head, and this condition is sometimes known as "water in the brain". People with this condition have abnormal accumulation of cerebrospinal fluid (CSF) in the ventricles, or cavities, of the brain.