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thun·der

(thŭndər)

1. The crashing or booming sound produced by rapidly expanding air along the path of the electrical discharge of lightning.

2. A sound that resembles or suggests thunder.

v. thun·dered, thun·der·ing, thun·ders

v.intr.

1. To produce thunder.

2. To produce sounds like thunder.

3. To move while making a loud noise: The express train thundered past us.

4. To utter loud, vociferous remarks or threats.

v.tr.

To express violently, commandingly, or angrily; roar.

[Middle English thonder, from Old English thunor; see (s)tenə- in the Appendix of Indo-European roots.]

thunder·er n.

Indo-European & Semitic Roots Appendices

Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

Indo-European Roots

Semitic Roots

The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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