Hŷ'dro-cĕph'a-lŭs, n.

n. [Gr. ὑδροκέφαλος and ὑδροκέφαλον, water in the head, from ὕδωρ, water, and κεφαλή, head; Fr. hydrocéphale.] (Med.) An accumulation of liquid within the cavity of the cranium; dropsy of the brain. When it occurs in infancy, it often enlarges the head enormously.