The Collaborative International Dictionary of English v.0.48:

Thunderbolt \Thun"der*bolt`\, n.
   1. A shaft of lightning; a brilliant stream of electricity
      passing from one part of the heavens to another, or from
      the clouds to the earth.
      [1913 Webster]

   2. Something resembling lightning in suddenness and
      effectiveness.
      [1913 Webster]

            The Scipios' worth, those thunderbolts of war.
                                                  --Dryden.
      [1913 Webster]

   3. Vehement threatening or censure; especially,
      ecclesiastical denunciation; fulmination.
      [1913 Webster]

            He severely threatens such with the thunderbolt of
            excommunication.                      --Hakewill.
      [1913 Webster]

   4. (Paleon.) A belemnite, or thunderstone.
      [1913 Webster]

   Thunderbolt beetle (Zool.), a long-horned beetle
      (Arhopalus fulminans) whose larva bores in the trunk of
      oak and chestnut trees. It is brownish and bluish-black,
      with W-shaped whitish or silvery markings on the elytra.
      [1913 Webster]

WordNet (r) 3.0 (2006):

thunderbolt
    n 1: a discharge of lightning accompanied by thunder [syn:
         thunderbolt, bolt, bolt of lightning]
    2: a shocking surprise; "news of the attack came like a
       bombshell" [syn: bombshell, thunderbolt, thunderclap]

Moby Thesaurus II by Grady Ward, 1.0:

71 Moby Thesaurus words for "thunderbolt":
   Jupiter Fulgur, Thor, antelope, arrow, astonishment,
   ball lightning, blockbuster, blow, blue darter, blue streak, bolt,
   bolt of lightning, bomb, bombshell, cannonball, catch,
   chain lightning, courser, dark lightning, dart, eagle, earthshaker,
   electricity, express train, eye-opener, fireball, firebolt, flash,
   flying flame, forked lightning, fulguration, fulmination, gazelle,
   greased lightning, greyhound, hare, jet plane, joker, kicker,
   levin bolt, light, lightning, mercury, oak-cleaving thunderbolts,
   peripeteia, quicksilver, revelation, rocket, scared rabbit,
   sheet lightning, shocker, shot, staggerer, startler, streak,
   streak of lightning, striped snake, stroke of lightning, surprisal,
   surprise, surprise ending, surprise package, surprise party,
   swallow, switch, thought, thunderball, thunderclap, thunderstroke,
   torrent, wind



U.S. Gazetteer Places (2000):

Thunderbolt, GA -- U.S. town in Georgia
   Population (2000):    2340
   Housing Units (2000): 1096
   Land area (2000):     1.273892 sq. miles (3.299364 sq. km)
   Water area (2000):    0.178161 sq. miles (0.461435 sq. km)
   Total area (2000):    1.452053 sq. miles (3.760799 sq. km)
   FIPS code:            76364
   Located within:       Georgia (GA), FIPS 13
   Location:             32.032111 N, 81.051733 W
   ZIP Codes (1990):
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Thunderbolt, GA
    Thunderbolt