1.A line of pipe with pumping machinery and apparatus for conveying liquids, gases, or finely divided solids, such as petroleum or natural gas, between distant points.
2.Fig. an information channel direct from the source.
3.The set of stages and processes from the invention or design of a product to its ultimate use, production, or commercial sale. Used commonly in the phrase in the pipeline, i. e. still in preparation or under development.