A pipeline is a long system of connected pipes that carries liquids or gases over great distances, like oil from wells in Texas to refineries on the coast, or natural gas from underground deposits to homes and power plants. These enormous tubes, sometimes buried underground and sometimes running above ground, can stretch for hundreds or even thousands of miles. Engineers build pipelines because they're efficient: once constructed, they can transport massive amounts of material cheaply and reliably, without needing trucks or trains making constant trips.

The word also describes any step-by-step process where things move from one stage to the next in order. A factory might have an assembly line pipeline where each worker adds one part to a product before passing it along. In sports, teams talk about their pipeline of young talent, meaning players developing through different levels who will eventually reach the major leagues. A movie studio might have several films in the pipeline, meaning they're at various stages of production but not yet released.

When something is in the pipeline, it means it's coming soon but isn't quite ready yet. Your teacher might say that a field trip is in the pipeline, meaning it's being planned and will happen eventually, even though the details aren't final.