1. [noun] A conduit made of pipes used to convey water, gas or petroleum etc
2. [noun] A channel (either physical or logical) by which information is transmitted sequentially (that is, the first information in is the first information out).
3. [noun] A system through which something is conducted
4. [noun] (surfing) The inside of a wave that a surfer is riding, when the wave has started closing over it.
5. [verb] (transitive) To convey something by a system of pipes
6. [verb] (transitive) To lay a system of pipes through something
7. [verb] (computing) (transitive) To design (a microchip etc.) so that processing takes place in efficient stages, the output of each stage being fed as input to the next.
8. [noun] Gossip spread by spoken communication; 'the news of their affair was spread by word of mouth'.
9. [noun] A pipe used to transport liquids or gases; 'a pipeline runs from the wells to the seaport'.