A rattling is a quick, often unsteady, burst of sounds. The sound of a rattlesnake is a good example of a rattling.
You know how a baby rattle sounds? That kind of quick collection of sounds can be called a rattling. A rattling is disjointed and fast. Some machines — like a car engine — make a rattling sound when they're broken. The rattling of a rattlesnake’s tail is a sign you could be in serious danger from this venomous snake. Sometimes a doctor will hear a rattling in the lungs that indicates a respiratory illness. A rattling can also be called a rattle.