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.