h

noun

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

   Synonyms

   • hydrogen, H, atomic number 1

   Less specific

   • chemical element, element, gas

   More specific

   • tritium

   Made from

   • water, H2O

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

   Synonyms

   • henry, H

   Less specific

   • inductance unit

   Parts

   • abhenry, millihenry

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

   Synonyms

   • Planck's constant

   Less specific

   • factor of proportionality, constant of proportionality

4. the 8th letter of the Roman alphabet

   Synonyms

   • H

   Less specific

   • letter, letter of the alphabet, alphabetic character

   Member of

   • Roman alphabet, Latin alphabet

5. (thermodynamics) a thermodynamic quantity equal to the internal energy of a system plus the product of its volume and pressure; “enthalpy is the amount of energy in a system capable of doing mechanical work”

   Synonyms

   • heat content, total heat, enthalpy, H

   Less specific

   • physical property