Source : Webster's Revised Unabridged Dictionary (1913)

Thunder \Thun"der\, n. [OE. [thorn]under, [thorn]onder,
   [thorn]oner, AS. [thorn]unor; akin to [thorn]unian to
   stretch, to thunder, D. donder thunder, G. donner, OHG.
   donar, Icel. [thorn][=o]rr Thor, L. tonare to thunder,
   tonitrus thunder, Gr. to`nos a stretching, straining, Skr.
   tan to stretch. [root]52. See {Thin}, and cf. {Astonish},
   {Detonate}, {Intone}, {Thursday}, {Tone}.]
   1. The sound which follows a flash of lightning; the report
      of a discharge of atmospheric electricity.

   2. The discharge of electricity; a thunderbolt. [Obs.]

            The revenging gods 'Gainst parricides did all their
            thunders bend.                        --Shak.

   3. Any loud noise; as, the thunder of cannon.

   4. An alarming or statrling threat or denunciation.

            The thunders of the Vatican could no longer strike
            into the heart of princes.            --Prescott.

   {Thunder pumper}. (Zo["o]l.)
      (a) The croaker ({Haploidontus grunniens}).
      (b) The American bittern or stake-driver.

   {Thunder rod}, a lightning rod. [R.]

   {Thunder snake}. (Zo["o]l.)
      (a) The chicken, or milk, snake.
      (b) A small reddish ground snake ({Carphophis, or Celuta,
          am[oe]na}) native to the Eastern United States; --
          called also {worm snake}.

   {Thunder tube}, a fulgurite. See {Fulgurite}.