Definitions of thunder:

• noun:   a booming or crashing noise caused by air expanding along the path of a bolt of lightning
• noun:   a deep prolonged loud noise
• noun:   street names for heroin
• verb:   move fast, noisily, and heavily

  Example: "The bus thundered down the road"

• verb:   be the case that thunder is being heard

  Example: "Whenever it thunders, my dog crawls under the bed"

• verb:   utter words loudly and forcefully
• verb:   to make or produce a loud noise

  Example: "The river thundered below"