WordNet (r) 3.0 (2006):

hydrocephaly
    n 1: an abnormal condition in which cerebrospinal fluid collects
         in the ventricles of the brain; in infants it can cause
         abnormally rapid growth of the head and bulging fontanelles
         and a small face; in adults the symptoms are primarily
         neurological [syn: hydrocephalus, hydrocephaly]