hydro-, hydra-, hydr-, hyd-

(Greek: water)

The regions beneath the ocean's surface, especially when considered as an area to be studied.
1. The water portion of the earth or biosphere; as distinguished from the solid part (lithosphere) and from the gaseous outer envelope (atmosphere).
2. The portion of the earth that is water, including liquid water, ice, and water vapor on the surface, underground, or in the atmosphere.
hydrosphygmography (s) (noun), hydrosphygmographies (pl)
1. A recording of blood pressure by means of a hydrosphygmograph using water as an index.
2. A sphygmograph in which the pulse beat is transmitted to the recorder through a column of water.

A sphygmograph is an instrument which, when applied over an artery, indicates graphically the movements or character of the pulse.

hydrostat (s) (noun), hydrostats (pl)
1. An electrical device designed to indicate or regulate the height of fluid in a column, reservoir, or other container: The hydrostat Jim was using was a good protection against the destruction of his building from leakage or flooding.
2. An apparatus that is used to prevent damage to a steam boiler when the water gets below a specified level: The hydrostat that Susan had on her pressure cooker gave a signal as a warning when the amount of water got too low.
1. The science of pressures and levels in water and hence in liquids generally.
2. The study of liquids at rest and the forces exerted on them or by them.
3. The study of liquids at rest as well as the forces and pressures associated with them.
Hydrotherapy combined with induced sweating, as in a Turkish bath.
Hydrotherapy combined with induced sweating as in a Turkish bath, sauna, etc.; also hidrotherapy.
hydrotaxis, hydrotactic
1. The directed response of a motile organism towards (positive) or away from (negative) a water or moisture stimulus.
2. Movement of an organism in response to water.
3. A movement or orientation directed by the presence of water.
hydrotechnic, hydrotechny
Relating to or dealing with the technical management or utilization of water.
1. Death caused by drowning.
2. Execution or accidental death by drowning.
hydrotheology (s) (noun), hydrotheologies (pl)
1. A discourse on theology which is not founded on revelation, but is based on reasoning from natural facts concerning water.
2. Characterized by natural theology.
A reference to hydrotherapy or hydrotherapeutics.
A specialist in or practitioner of hydrotherapy.
hydrotherapy, hydrotherapeutics
1. Treatment of an illness with water by external application, either for its pressure effect or as a means of applying physical energy to the tissues.
2. The external application of water; such as, in warm baths to relax or with cold compresses to reduce fevers.
hydrothermal vent
1. A fissure in the sea bottom through which hot aqueous solutions rise from the magma beneath the crust.
2. A geyser on the sea bottom through which super-hot aqueous solutions rise from the magma beneath the earth's crust.

This creates a surrounding system of mineral-rich water which helps to support a distinctive type of ecosystem not found in typical cold-water environments at the same ocean depth.

Cross references of word families that refer to "water": aqua-; hydat-; hygro-.