The Collaborative International Dictionary of English v.0.48:

Herald \Her"ald\, n. [OE. herald, heraud, OF. heralt, heraut,
   herault, F. h['e]raut, LL. heraldus, haraldus, fr. (assumed)
   OHG. heriwalto, hariwaldo, a (civil) officer who serves the
   army; hari, heri, army + waltan to manage, govern, G. walten;
   akin to E. wield. See Harry, Wield.]
   1. (Antiq.) An officer whose business was to denounce or
      proclaim war, to challenge to battle, to proclaim peace,
      and to bear messages from the commander of an army. He was
      invested with a sacred and inviolable character.
      [1913 Webster]

   2. In the Middle Ages, the officer charged with the above
      duties, and also with the care of genealogies, of the
      rights and privileges of noble families, and especially of
      armorial bearings. In modern times, some vestiges of this
      office remain, especially in England. See Heralds'
      College (below), and King-at-Arms.
      [1913 Webster]

   3. A proclaimer; one who, or that which, publishes or
      announces; as, the herald of another's fame. --Shak.
      [1913 Webster]

   4. A forerunner; a a precursor; a harbinger.
      [1913 Webster]

            It was the lark, the herald of the morn. --Shak.
      [1913 Webster]

   5. Any messenger. "My herald is returned." --Shak.
      [1913 Webster]

   Heralds' College, in England, an ancient corporation,
      dependent upon the crown, instituted or perhaps recognized
      by Richard III. in 1483, consisting of the three
      Kings-at-Arms and the Chester, Lancaster, Richmond,
      Somerset, Windsor, and York Heralds, together with the
      Earl Marshal. This retains from the Middle Ages the charge
      of the armorial bearings of persons privileged to bear
      them, as well as of genealogies and kindred subjects; --
      called also College of Arms.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Herald \Her"ald\, v. t. [imp. & p. p. Heralded; p. pr. & vb.
   n. Heralding.] [Cf. OF. herauder, heraulder.]
   To introduce, or give tidings of, as by a herald; to
   proclaim; to announce; to foretell; to usher in. --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

herald
    n 1: (formal) a person who announces important news; "the
         chieftain had a herald who announced his arrival with a
         trumpet" [syn: herald, trumpeter]
    2: something that precedes and indicates the approach of
       something or someone [syn: harbinger, forerunner,
       predecessor, herald, precursor]
    v 1: foreshadow or presage [syn: announce, annunciate,
         harbinger, foretell, herald]
    2: praise vociferously; "The critics hailed the young pianist as
       a new Rubinstein" [syn: acclaim, hail, herald]
    3: greet enthusiastically or joyfully [syn: hail, herald]

Moby Thesaurus II by Grady Ward, 1.0:

119 Moby Thesaurus words for "herald":
   Clarenceux, College of Arms, Gabriel, Garter, Lyon, Norroy,
   Norroy and Ulster, ancestor, announce, announcer, antecede,
   antecedent, antedate, anticipate, avant-garde, ballyhoo, be before,
   be early, bellwether, blare, blare forth, blaze, blaze abroad,
   blaze the trail, blazon, blazon about, break the trail, buccinator,
   buccinator novi temporis, bushwhacker, celebrate, come before,
   commissar, commissary, commissionaire, commissioner, courier,
   crier, cry, cry out, declaim, delegate, earl marshal, emissary,
   envoy, evangel, evangelist, explorer, forebear, foregoer, forerun,
   forerunner, foreshadower, foreshow, front runner, frontiersman,
   fugleman, give notice, go before, groundbreaker, guide, harbinger,
   herald abroad, herald angel, innovator, introduce, king at arms,
   king of arms, lead, lead runner, leader, legate, messenger,
   minister, mouthpiece, notify, official spokesman, outrider,
   pathfinder, pioneer, point, preannounce, precede, precedent,
   precurse, precursor, predate, predecessor, preexist, preindicate,
   premonitor, presage, presager, proclaim, prolocutor, prolocutress,
   prolocutrix, promulgate, rapporteur, reporter, run before, scout,
   secretary, shout, speaker, spokesman, spokeswoman, stormy petrel,
   thunder, thunder forth, trailblazer, trailbreaker, trumpet,
   trumpet forth, usher in, vanguard, vaunt-courier, voice,
   voortrekker