A muted sound of complaint or discontent. / A deep low noise.

present participle of rumble

plural of rumbling

Making a rumbling noise.

(dated) An extra passenger seat or row of seats in an automobile, which typically folds away into a rear storage compartment. / (aviation, colloquial) A jump seat.

plural of rumble seat

(obsolete) scrambled eggs

plural of rumble strip

A pattern of variation in a road's surface designed to alert inattentive drivers to potential danger by causing a tactile vibration and audible rumbling if they veer out of their lane.

(dated) A rumble seat.