Definitions for "Pipelines"
Any pipe with a nominal diameter of 6 inches or more that is designed to transport hazardous liquids, but does not include pipe designed to transport a hazardous liquid by gravity, and pipe designed to transport or store a hazardous liquid within a refining, storage or manufacturing facility; or pipe designed to be operated at a pressure of more than 275 pounds per square inch and to carry gas as defined.
In modern CPUs, information is broken down into smaller parts to allow for more efficient processing. These parts are sent to pipelines to be executed. The number of pipelines a CPU has determines how many steps an instruction can be broken down into.