1. （常指埋于地下的石油或燃气）管道，管线
A pipeline is a large pipe which is used for carrying oil or gas over a long distance, often underground.

2. 在筹备中；在进行中
If something is in the pipeline, it has already been planned or begun.

1. a pipe used to transport liquids or gases

e.g. a pipeline runs from the wells to the seaport

Synonym: line

2. gossip spread by spoken communication

e.g. the news of their affair was spread by word of mouth

Synonym: grapevineword of mouth