mainline

中文： 干线、主线

1. An airline's main operating unit, as opposed to codeshares or regional subsidiaries.
2. The principal route or line of a railway.
3. In longline fishing the central line to which the branch lines with baits are attached.
4. The pipeline carrying wastewater to the public drains or a septic tank.
5. A principal vein into which a drug can be injected. (slang)
6. The main repository for a software project, from which different versions (forks) may be split off.
7. The general population of a prison.

复数 mainlines