To integrate (code, etc.) into the main repository for a software project, rather than separate forks.
To inject (a drug) directly into a vein.
To consume voraciously.
Normal, principal or standard.
Of or pertaining to the principal route or line of a railway.
Of or pertaining to a surface railway as distinct from an underground, elevated or light rail one.
Of a sequence of opening moves: being part of a main line ("a standard sequence of opening moves considered to be best play").
In longline fishing the central line to which the branch lines with baits are attached.
An airline's main operating unit, as opposed to codeshares or regional subsidiaries.
The principal route or line of a railway.
A principal vein into which a drug can be injected.
The main repository for a software project, from which different versions (forks) may be split off.
The pipeline carrying wastewater to the public drains or a septic tank.
petty; not important or noteworthy