Definitions

1. noun

a low, continuous rumbling or vibrating sound, especially one caused by thunder or an earthquake

“The rumb of the distant thunder made it hard to sleep.”

2. verb

to make a low rumbling or vibrating sound

“The engine was rumbling as the pilot started the plane.”

3. verb

to make a loud, low-pitched sound, especially one caused by a rolling object

“The wheels rumbled over the cobblestone street.”