definition of
H

[1] #1 H n. [hydrogen, atomic number 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. wn

[2] #2 H n. [henry] 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. wn

[3] #3 H n. [Planck's constant, h] the constant of proportionality relating the energy of a photon to its frequency; approximately 6.626 x 10^-34 joule-second. wn

[4] #4 H n. [h] the 8th letter of the Roman alphabet. wn

[5] #5 H n. [h] the 8th letter of the Roman alphabet. wn