Source : Webster's Revised Unabridged Dictionary (1913)

H \H\ (h[add]). (Mus.)
   The seventh degree in the diatonic scale, being used by the
   Germans for B natural. See {B}.

H \H\ ([=a]ch),
   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, [th], as in
   shall, thing, [th]ine (for zh see [sect]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}, [sect][sect] 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. [eta]. The Greek H is from Ph[oe]nician, 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. [.c]ata.

   {H piece} (Mining), the part of a plunger pump which contains
      the valve.

Source : WordNet®

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}]

Source : Free On-Line Dictionary of Computing

h
     
        1. A simple {markup} language intended for quick conversion of
        existing text to {hypertext}.
     
        2. A method of marking common words to call attention to the
        fact that they are being used in a nonstandard, ironic, or
        humorous way.  Originated in the fannish catchphrase "Bheer
        is the One True Ghod!" from decades ago.  H-infix marking of
        "Ghod" and other words spread into the 1960s counterculture
        via underground comix, and into early hackerdom either from
        the counterculture or from SF fandom (the three overlapped
        heavily at the time).  More recently, the h infix has become
        an expected feature of benchmark names (Dhrystone, Rhealstone,
        etc.); this follows on from the original Whetstone (the name
        of a laboratory) but may have been influenced by the
        fannish/counterculture h infix.
     
        [{Jargon File}]
     
        (1994-11-04)