hydrangea /hī-drānˈjə or hī-drānˈjyə/ noun

(Gr angeion vessel) a plant of the Hydrangea genus of shrubby plants of the family Hydrangeāˈceae, with large globular clusters of showy flowers, natives of China and Japan

hydrant /hīˈdrənt/ noun

A connection for attaching a hose to a water main or a fireplug

hydranth /hīˈdranth/ noun

(Gr anthos flower) a nutritive polyp in a hydroid colony

hydrarthrōˈsis noun (medicine)

Swelling of a joint caused by the accumulation in it of watery fluid

hyˈdrate noun

1. A chemical combination of a substance and water which can be expelled without affecting the composition of the substance
2. An old word for a hydroxide (see under hydro-²)

transitive verb

1. To combine with water
2. To cause to absorb water (hydrated electron a very reactive free electron released in aqueous solutions by the action of ionizing radiations; hydrated ion an ion surrounded by molecules of water which it holds in a degree of orientation)

hydrāˈtion noun

hydrēˈmia noun

Mainly N American form of hydraemia

hyˈdric adjective

1. Relating to an abundance of moisture
2. See also under hydrogen

hyˈdrically adverb

hydride noun see under hydrogen

hydro-aeˈroplane (N American hydro-airˈplane) noun

A seaplane

hydrobiologˈical adjective

hydrobiolˈogist noun

hydrobiolˈogy noun

The biology of aquatic animals and plants

hyˈdrocele /-sēl/ noun (Gr kēlē a swelling; medicine)

A swelling containing serous fluid, esp in the scrotum

hydrocellˈūlose noun

A gelatinous material obtained by hydration of cellulose, used in paper-making, etc

hydrocephalˈic or hydrocephˈalous adjective

hydrocephalus /-sefˈə-ləs or -kefˈ/ noun

1. (Gr kephalē head) an accumulation of serous fluid within the cranial cavity, either in the subdural space or the ventricles
2. Water in the head
3. Dropsy of the brain

Hydrocharis /hī-drokˈə-ris/ noun

(Gr charis, -itos grace) the frogbit genus, giving name to the Hydrocharitāˈceae, a family of water plants related to the pondweeds

hyˈdrochore /-kör/ noun

(Gr chōreein to make room, spread about) a plant disseminated by water

hydrochoric /-korˈik/ adjective

hydrocollˈoid noun

A substance that forms a gel when mixed with water

Hydrocorallīˈnae plural noun

An order of Hydrozoa, massive reef-builders, the millepores, etc

hydrocorˈalline noun and adjective

hydrodynamic /-dīn-amˈik/ or hydrodynamˈical adjective (Gr dynamis power)

hydrodynamˈicist noun

hydrodynamˈics singular noun

The science of the motions and equilibrium of a material system partly or wholly fluid (called hydrostatics when the system is in equilibrium, hydrokinetics when it is not)

hydroelastˈic adjective

(hydroelastic suspension a system of car suspension in which a fluid provides interconnection between the front and rear suspension units)

hydroelecˈtric adjective

hydroelectricˈity noun

Electricity produced by means of water, esp by water power

hydroextractˈor noun

A drying machine that works centrifugally

hyˈdrofoil noun

1. A device on a boat for raising it from the water as its speed increases
2. A boat fitted with this device
3. A corresponding device on a seaplane to aid its take-off (also hyˈdrovane)
4. A seaplane with hydrofoils

hyˈdrogel noun

A gel formed with water

hydrogeolˈogist noun

hydrogeolˈogy noun

The branch of geology dealing with ground water

hyˈdrograph noun

A graph showing seasonal variations in level, force, etc of a body of water

hydrogˈrapher noun

(Gr graphein to write)

hydrographic /-grafˈik/ or hydrographˈical adjective

hydrographˈically adverb

hydrogˈraphy noun

The investigation of seas and other bodies of water, including charting, sounding, study of tides, currents, etc

hyˈdroid adjective

1. Like a Hydra
2. Polypoid

noun

1. A hydrozoan
2. A hydrozoan in its asexual generation

hydrokinetˈic adjective

1. Relating to hydrokinetics
2. Relating to the motion of fluids
3. Relating to fluids in motion
4. Operated or operating by the movement of fluids

hydrokinetˈics singular noun see hydrodynamics above

hyˈdrolase noun

An enzyme that catalyses hydrolysis

hydrologˈic or hydrologˈical adjective

hydrologˈically adverb

hydrolˈogist noun

hydrolˈogy noun

1. The study of water resources in land areas of the world
2. The study of underground water resources (US)

hydrolˈysate /-i-sāt/ noun

A substance produced by hydrolysis

hydrolyse or (N American) hydrolyze /hīˈdrō-līz/ transitive verb

To subject to hydrolysis (also intransitive verb)

hydrolysis /hī-drolˈi-sis/ noun

(Gr lysis loosing) chemical decomposition or ionic dissociation caused by water

hyˈdrolyte /-līt/ noun

A body subjected to hydrolysis

hydrolytic /-litˈik/ adjective

hydromagnetˈic adjective

hydromagnetˈics singular noun

Magnetohydrodynamics

hyˈdromancy noun

(Gr manteiā divination) divination by water

hydromāˈnia noun

A craving for water

hydromantˈic adjective

hydromechanˈics singular noun

Hydrodynamics

hydromedūˈsa noun

A hydrozoan in its sexual generation

Hydromedūˈsae plural noun

The class Hydrozoa

hydromedūˈsan or hydromedūˈsoid adjective

(also noun)

hyˈdromel noun

1. (Gr hydromeli, from meli honey) a beverage made of honey and water
2. Mead

hydrometˈallurgy (or /-met-alˈər-ji/) noun

The extraction of metal from ore by treatment with water or other fluids

hydromēˈteor noun

(Gr meteōron a meteor) any weather phenomenon depending on the moisture content of the atmosphere

hydrometeorolˈogy noun

hydromˈeter noun

(Gr metron a measure) an instrument for measuring specific gravity

hydrometric /-metˈ/ or hydrometˈrical adjective

hydromˈetry noun

The science of the measurement and analysis of water, including the methods, techniques and instrumentation used in hydrology

Hydromys /hīˈdrō-mis/ noun

(Gr mȳs mouse) an Australasian genus of aquatic rodents

hyˈdronaut noun

A person trained to work in an underwater vessel, eg a submarine

hydronephrōˈsis noun

Distension of the kidney with urine held up as a result of obstruction in the urinary tract

hydronephroˈtic adjective

hydropathic /hī-drō-pathˈik or hī-drə-/ adjective

Of, for, relating to or practising hydropathy

noun (in full hydropathic establishment; informal hyˈdro (pl hyˈdros)

) a hotel (with special baths, etc, and often situated near a spa) where guests can have hydropathic treatment

hydropathˈical adjective

hydropathˈically adverb

hydropˈathist noun

A person who practises hydropathy

hydropˈathy noun

(Gr pathos suffering) the treatment of disease by water, externally and internally

hydrophane /hīˈdrō-fān/ noun

(Gr phānos bright) a translucent opal transparent in water

hydrophanous /-drofˈən-əs/ adjective

Transparent on immersion

Hydrophidae /hī-drofˈi-dē/ plural noun

(Gr ophis snake) a family of venomous sea snakes

hydrophilˈic adjective (chem)

Attracting water

hydrophˈilite noun

Native calcium chloride (a very hygroscopic mineral)

hydrophˈilous adjective

1. Water-loving
2. Pollinated by agency of water (botany)

hydrophˈily noun

(Gr phileein to love) water-pollination

hydrophōˈbia noun

1. (Gr phobos fear) horror of water
2. Inability to swallow water owing to a contraction in the throat, a symptom of rabies
3. Rabies itself

hydrophōˈbic (or /-fobˈ/) adjective

1. Relating to hydrophobia
2. Repelling water (chem)

hydrophobicˈity noun

hydrophobous /-drofˈə-bəs/ adjective (obsolete)

hyˈdrophone /-fōn/ noun

(Gr phōnē voice) an apparatus for listening to sounds conveyed by water

hyˈdrophyte /-fīt/ noun

(Gr phyton plant) a plant growing in water or in very moist conditions

hydrophytic /-fitˈik/ adjective

hydrophyton /hī-drofˈi-ton/ noun

The coenosarc of a hydroid colony

hydrophˈytous adjective

hydropˈic adjective (non-standard hydropˈtic; see hydropsy below)

1. Dropsical
2. Thirsty
3. Charged or swollen with water

hyˈdroplane noun

1. A light, flat-bottomed motorboat which, at high speed, skims along the surface of the water
2. A hydro-aeroplane or seaplane (non-standard)

intransitive verb

1. (of a boat) to skim like a hydroplane
2. (of a vehicle) to skid on a wet road

hydropneumatˈic adjective

Utilizing water and air acting together

hydropolˈyp noun

A hydrozoan polyp

hydroponˈic adjective

hydroponˈically adverb

hydroponics /hī-drō-ponˈiks/ singular noun

(Gr ponos toil) the art or practice of growing plants in (sand or gravel containing) a chemical solution without soil

hyˈdropower noun

Hydroelectric power

hyˈdropsy noun (Gr hydrōps dropsy; archaic)

Dropsy

Hydropteridˈeae /-i-ē/ plural noun

(Gr pteris, -idos male-fern) the water ferns or heterosporous ferns

hydroptic adjective see hydropic above

hyˈdropult noun

(modelled on catapult) a hand force pump

hydroquinone /-kwin-ōnˈ, or kwinˈ or -kwīnˈ/ noun

Quinol

hyˈdroscope noun

1. (Gr skopeein to view) a kind of water clock, a graduated tube, from which the water escaped (historical)
2. An instrument for viewing under water

hyˈdroski /-skē/ noun

A kind of hydrofoil used on seaplanes as a source of hydrodynamic lift, and on aeroplanes to make them amphibious

hydrosōˈma or hyˈdrosome /-sōm/ noun (pl hydrosōˈmata or hyˈdrosomes)

(Gr sōma body) a hydroid colony

hydrosōˈmal or hydrosōˈmatous adjective

hyˈdrospace or hydrosphere /hīˈdrō-sfēr/ noun

(Gr sphaira sphere) the water on the surface of the earth, the seas and oceans

hyˈdrostat noun

(Gr -statēs causing to stand) a contrivance for indicating the presence of water

hydrostatˈic or hydrostatˈical adjective

(hydrostatic balance a balance for weighing bodies in water to determine their specific gravity; hydrostatic drive or transmission (in a vehicle) a drive consisting of a system transmitting power through oil, under pressure; hydrostatic extrusion (metallurgy) a form of extrusion in which the metal to be shaped is preshaped to fit a die forming the lower end of a high-pressure container that is filled with a pressure-transmitting liquid, the pressure being built up in the liquid by a plunger until the metal is forced through the die; hydrostatic paradox the principle that any quantity of fluid, however small, may balance any weight, however great; hydrostatic press a hydraulic press)

hydrostatˈics singular noun see hydrodynamics above

hydrostatˈically adverb

hydrotacˈtic adjective

hydrotaxˈis noun

(Gr taxis arrangement) response of an organism to the stimulus of water

hydrothēˈca noun

(Gr thēkē case) the horny cup of a hydranth

hydrotherapeuˈtic adjective

hydrotherapeuˈtics or hydrotherˈapy noun

Treatment of disease by the external use of water, eg treatment of disability by developing movement in water

hydrotherˈmal adjective

Relating to or produced by the action of heated or superheated water, esp in dissolving, transporting and redepositing mineral matter

hydrothorax /-thöˈ/ noun

(Gr thōrax chest) oedema in the chest

hydrotropˈic adjective

hydrotˈropism noun

(Gr tropos a turn) the turning of a plant root towards (positive) or away from (negative) moisture

hydrous /-hīˈdrəs/ adjective (chem and mineralogy)

Containing water

hydrovane noun see hydrofoil above

hydrozincite /-zingkˈīt/ noun

Basic zinc carbonate

Hydrozōˈa plural noun

1. (Gr zōion an animal) a class of Coelenterata, chiefly marine organisms such as the zoophytes, millepores, etc, in which alternation of generations typically occurs, the hydroid phase colonial giving rise to the medusoid phase by budding
2. Sometimes extended to include the true jellyfishes
3. (without cap) hydrozoans

hydrozōˈan noun and adjective

hydrozōˈon noun (pl hydrozōˈa)

A coelenterate of the Hydrozoa