mainline.

Normal, principal or standard.

Not fundamentalist, charismatic or evangelical.

Of or pertaining to the principal route or line of a railway.

Of or pertaining to a surface-level heavy rail system as distinct from an underground, elevated or light rail one.

Of or pertaining to national or long-distance rail network operators as opposed to urban and suburban operators.

Pertaining to a direct route between two major ports.

Of a sequence of opening moves: being part of a main line ("a standard sequence of opening moves considered to be best play").

To inject (a drug) directly into a vein.

To consume voraciously.

To integrate (code, etc.) into the main repository for a software project, rather than separate forks.

To include (a prisoner) in the general population of a prison.

An airline's main operating unit, as opposed to codeshares or regional subsidiaries.

The principal route or line of a railway.

In longline fishing the central line to which the branch lines with baits are attached.

The pipeline carrying wastewater to the public drains or a septic tank.

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.

Alternative form of main line.

The general population of a prison.