H

Pronunciation (US):

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 Dictionary entry overview: What does H mean? 

• H (noun)
  The noun H has 5 senses:

1. a nonmetallic univalent element that is normally a colorless and odorless highly flammable diatomic gas; the simplest and lightest and most abundant element in the universe

2. a unit of inductance in which an induced electromotive force of one volt is produced when the current is varied at the rate of one ampere per second

3. the constant of proportionality relating the energy of a photon to its frequency; approximately 6.626 x 10^-34 joule-second

4. the 8th letter of the Roman alphabet

5. (thermodynamics) a thermodynamic quantity equal to the internal energy of a system plus the product of its volume and pressure

  Familiarity information: H used as a noun is common.

 Dictionary entry details 

• H (noun)

Sense 1

Meaning:

A nonmetallic univalent element that is normally a colorless and odorless highly flammable diatomic gas; the simplest and lightest and most abundant element in the universe

Classified under:

Nouns denoting substances

Synonyms:

atomic number 1; H; hydrogen

Hypernyms ("H" is a kind of...):

chemical element; element (any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter)

gas (a fluid in the gaseous state having neither independent shape nor volume and being able to expand indefinitely)

Hyponyms (each of the following is a kind of "H"):

tritium (a radioactive isotope of hydrogen; atoms of tritium have three times the mass of ordinary hydrogen atoms)

Holonyms ("H" is a substance of...):

H2O; water (binary compound that occurs at room temperature as a clear colorless odorless tasteless liquid; freezes into ice below 0 degrees centigrade and boils above 100 degrees centigrade; widely used as a solvent)

Sense 2

Meaning:

A unit of inductance in which an induced electromotive force of one volt is produced when the current is varied at the rate of one ampere per second

Classified under:

Nouns denoting quantities and units of measure

Synonyms:

H; henry

Hypernyms ("H" is a kind of...):

inductance unit (a measure of the property of an electric circuit by which an electromotive force is induced in it)

Meronyms (parts of "H"):

abhenry (a unit of inductance equal to one billionth of a henry)

millihenry (a unit of inductance equal to one thousandth of a henry)

Sense 3

Meaning:

The constant of proportionality relating the energy of a photon to its frequency; approximately 6.626 x 10^-34 joule-second

Classified under:

Nouns denoting quantities and units of measure

Synonyms:

h; Planck's constant

Hypernyms ("h" is a kind of...):

constant of proportionality; factor of proportionality (the constant value of the ratio of two proportional quantities x and y; usually written y = kx, where k is the factor of proportionality)

Sense 4

Meaning:

The 8th letter of the Roman alphabet

Classified under:

Nouns denoting communicative processes and contents

Hypernyms ("H" is a kind of...):

alphabetic character; letter; letter of the alphabet (the conventional characters of the alphabet used to represent speech)

Holonyms ("H" is a member of...):

Latin alphabet; Roman alphabet (the alphabet evolved by the ancient Romans which serves for writing most of the languages of western Europe)

Sense 5

Meaning:

(thermodynamics) a thermodynamic quantity equal to the internal energy of a system plus the product of its volume and pressure

Classified under:

Nouns denoting attributes of people and objects

Synonyms:

enthalpy; H; heat content; total heat

Context example:

enthalpy is the amount of energy in a system capable of doing mechanical work

Hypernyms ("H" is a kind of...):

physical property (any property used to characterize matter and energy and their interactions)

Domain category:

thermodynamics (the branch of physics concerned with the conversion of different forms of energy)

 Context examples 

This agent displays selectivity activity towards both hypoxic solid tumors, which exhibits higher expression of cytochrome P450 reductase, and well-oxygenated malignant cells that overexpress the bioreductive enzyme NQO1 (NAD(P)H: quinone oxidoreductase).

(Apaziquone, NCI Thesaurus)

Another aspect of the inflammatory response to H. influenzae infection is the production of excessive mucus, contributing to the overall symptoms of infection.

(NFKB Activation Pathway, NCI Thesaurus/BIOCARTA)

Zapata flew across the water at over 100 mph (161 km/h).

(French inventor Franky Zapata successfully crosses English Channel on jet-powered hoverboard, Wikinews)

“Of course you saw the ‘J.H.’ monogram on my locket,” said he.

(The Memoirs of Sherlock Holmes, by Sir Arthur Conan Doyle)

NAD(P)H dehydrogenase [quinone] 1 (274 aa, ~31 kDa) is encoded by the human NQO1 gene.

(NAD(P)H Dehydrogenase [Quinone] 1, NCI Thesaurus)

The determination of the amount of apolipoprotein H present in a sample.

(Apolipoprotein H Measurement, NCI Thesaurus)

Natural latex is an extract of the rubber tree (H. brasiliensis) and contains the allergens responsible for latex hyper-sensitivity reactions.

(Natural Rubber, Food and Drug Administration)

C-X8-C-X5-C-X3-H type zinc finger proteins often function in cell cycle or growth regulation, e.g. human TIS11B (butyrate response factor 1) and mouse TTP nuclear protein.

(C3H1 Zinc Finger, NCI Thesaurus)

The Ah receptor/ARNT heterodimer binds to dioxin-responsive elements and alters expression of a number of genes including; CYP1A1, CYP1A2, CYP1B1, and NAD(P)H quinone oxidoreductase.

(AHR Signal Transduction Pathway, NCI Thesaurus/BIOCARTA)

Hélène Seroussi and Erik Ivins of JPL found that the flux of energy from the mantle plume must be no more than 150 milliwatts per square meter.

(Hot News from the Antarctic Underground, NASA)