noun, American English - the official set of rules, advice, and information about how to drive and behave on the road (esp. in the UK)
noun, British English - the official set of rules, advice, and information about how to drive and behave on the road (esp. in the UK)
noun - a situation in which one event or action causes a series of other events to happen, like ripples spreading on water
noun - a situation in which many people are killed violently, especially in a short period of time or in a brutal way