Tail back Definition 1 of 2Pro Tip 1/3Traffic Jams Used to describe a common issue in traffic where cars are stopped or moving slowly. Expect to tail back during rush hour. Pro Tip 2/3Extent of Delay It emphasizes the length of the traffic jam, indicating a significant waiting period. The tail back stretched for several kilometers. Pro Tip 3/3Unexpected Events It often results from unforeseen events like accidents or road construction. Due to the parade, traffic began to tail back.