engines running
- motorsMachines that produce motion
- hummingContinuous low-pitched sound
- idlingOperating without working
- revvingIncreasing engine speed
- exhaustUse up entirely
rumble · throttle · purring · vibration · fuel · pistons · turbines · roaring · horsepower · acceleration · ignition · diesel · gasoline · machinery · propulsion · throbbing · warmup · RPM
sound/activity presence
engines runningsilence
Total lack of sound
stillness · quiet · dead silence · all quiet · motionless