Dictionary definition · thunder
noun
- a deep prolonged loud noise
- a booming or crashing noise caused by air expanding along the path of a bolt of lightning
- street names for heroin
verb
- move fast, noisily, and heavily"The bus thundered down the road"
- utter words loudly and forcefully"‘Get out of here,’ he roared"
- be the case that thunder is being heard"Whenever it thunders, my dog crawls under the bed"
- to make or produce a loud noise"The river thundered below"
Source: Open English WordNet (CC BY 4.0).