h /ˈeʧ/
 字母h


 H the eighth letter of the English alphabet, is classed among the consonants, and is formed with the mouth organs in the same position as that of the succeeding vowel. It is used with certain consonants to form digraphs representing sounds which are not found in the alphabet, as sh, th, , as in shall, thing, (for zh see §274); also, to modify the sounds of some other letters, as when placed after c and p, with the former of which it represents a compound sound like that of tsh, as in charm (written also tch as in catch), with the latter, the sound of f, as in phase, phantom. In some words, mostly derived or introduced from foreign languages, h following c and g indicates that those consonants have the hard sound before e, i, and y, as in chemistry, chiromancy, chyle, Ghent, Ghibelline, etc.; in some others, ch has the sound of sh, as in chicane.  See Guide to Pronunciation, §§ 153, 179, 181-3, 237-8.
 Note: The name (aitch) is from the French ache; its form is from the Latin, and this from the Greek H, which was used as the sign of the spiritus asper (rough breathing) before it came to represent the long vowel, Gr. η. The Greek H is from Phœnician, the ultimate origin probably being Egyptian. Etymologically H is most closely related to c; as in E. horn, L. cornu, Gr. ke`ras; E. hele, v. t., conceal; E. hide, L. cutis, Gr. ky`tos; E. hundred, L. centum, Gr. "e-kat-on, Skr. çata.
 H piece Mining, the part of a plunger pump which contains the valve.

From: Webster's Revised Unabridged Dictionary (1913)

 H Mus. The seventh degree in the diatonic scale, being used by the Germans for B natural. See B.

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From: WordNet (r) 2.0

 H
      n 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
           [syn: hydrogen, atomic number 1]
      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 [syn: henry]
      3: the constant of proportionality relating the energy of a
         photon to its frequency; approximately 6.626 x 10\-34
         joule-second [syn: Planck's constant]
      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; "enthalpy is the amount of energy in a
         system capable of doing mechanical work" [syn: {heat
         content, total heat, enthalpy]