mainline
Noun pluralmainlines
Verbmainlines, mainlining, mainlined
Pluralmainlines
Formsmainlines, mainlining, mainlined
- 1Being the normal, principal, or standard kind rather than a marginal or alternative one.
The festival drew acts from both indie labels and mainline studios.
Her views fell well outside mainline economic thinking at the time.
Similarmainstream
Note
Main plus line, fused into one word: a principal route turned into a label for whatever counts as the established center. Its most settled home is religion. There, mainline denominations, mainline congregations and mainline Protestantism name the long-established churches, set against independent or charismatic ones. Mainstream is its close synonym. Like most adjectives of this kind it does not take degrees: a church is mainline or it is not.
- 2The principal route or line of a railway, carrying the bulk of through traffic.
Express services use the mainline, while local trains divert onto branch routes.
Engineers electrified the mainline to allow faster intercity travel.
- 3Relating to the principal route or line of a railway.
Mainline services resumed once the signal fault was fixed.
The town finally got a mainline connection to the capital.
Note
Railway talk turns the noun into a label placed before another noun: mainline services, a mainline connection, mainline track. The contrast here is with branch and secondary lines, the trunk route as against its offshoots. Railway writers also use the word for surface rail versus metro, so check which contrast a sentence intends. A mainline station may simply be on the trunk route, or it may be heavy rail rather than underground.
- 4To inject a drug straight into a vein.
By his twenties he was mainlining whatever he could afford.
Addicts who mainline the drug risk collapsing their veins.
Note
Drug-user slang that names the method by its target, the vein itself. It is defined partly against skin-popping, injecting under the skin, as in Brotman and Freedman's 1968 study, where a patient skin-popped for a year and a half before starting to mainline heroin. The clipped verb main means the same thing. Outside clinical or documentary writing it reads as street language.
- 5An airline's main operating unit, separate from its regional subsidiaries or codeshare partners.
The carrier shifted several short routes from the mainline to its regional partners.
Mainline pilots earn considerably more than those at the affiliated regional airlines.
Note
Airline industry usage sets the carrier's own operation against everything that feeds it: regional subsidiaries, affiliates and codeshare partners. The word works as a noun (routes moved from the mainline) and, even more often, before another noun, as in mainline pilots and mainline flights. The distinction matters in labor and scheduling talk, where pay and contracts differ sharply between mainline and regional crews.
- 6In software development, to merge code into a project's main repository rather than keeping it in a separate fork.
Maintainers mainlined the patch after months of review.
The community pushed to mainline the driver into the kernel.
Note
Developers made a verb from the main repository: to mainline something is to get it accepted there rather than leaving it in a fork. The usual objects are a patch, a driver or a feature, and the phrase is often "mainline X into" a project, such as the kernel. Being mainlined is the goal of most outside contributions, because a merged change is then maintained along with the official code.
- 7The main repository of a software project, from which separate versions, or forks, can be split off.
Each fork eventually drifted far from the mainline.
Contributors submit their changes back to the mainline for review.
Similartrunk
- 8A major vein used for injecting a drug directly into the bloodstream.
Years of injecting had ruined every usable mainline in his arms.
She rolled up her sleeve looking for a mainline.
Note
Here the drug-user slang names the vein rather than the act. Its best-known appearance is Lou Reed's "Sister Ray" (1968), where the speaker hunts for his mainline and cannot get at it from an angle. The lyric captures the user's problem of finding a usable vein. The word belongs to street and literary registers. In medical settings you would simply say vein.
- 9To consume something greedily and without restraint.
Fans mainline the entire series in a single weekend.
He mainlined espresso to finish the report on time.
Note
The figure comes straight from the injecting sense: taking something in as fast and as directly as possible. Today it is a casual word for bingeing on entertainment. Jason Horowitz writes in 2022 of a politician too busy for mainlining Amazon's "Rings of Power" series. It is transitive, and it keeps a faint, deliberate edge of addiction. That makes it playful in conversation but unsuitable for formal prose.
- 10Relating to a surface railway, as distinct from an underground, elevated, or light rail system.
Mainline rail connects the suburbs to the city, while the metro serves the center.
The mainline network uses heavier track than the tram lines.
- 11Of an opening sequence, forming part of the standard moves considered best play.
The mainline variation of the Sicilian runs many moves deep.
Most grandmasters follow the mainline continuation in this position.
Note
Chess commentators put it straight in front of a move, a variation or a body of analysis: the mainline 3 e6, mainline theory, a mainline Nimzo-Indian. Avoiding mainline theory is a recognized match strategy, as Leonard Barden notes of Nigel Short. The adjective is formally ungraded, but writers bend that rule. A fairly mainline game is one that keeps close to the standard path without following it all the way.
- 12To place a prisoner among the general population of a prison.
Officials chose to mainline the prisoner once the threat assessment cleared him.
The facility mainlined the transfers into general housing the same day.
- 13The general body of ordinary inmates in a prison.
After sentencing, she was released into the mainline.
Guards monitor the mainline closely during meal times.
Note
Prison vocabulary for ordinary housing, defined by what it is not: segregation, protective custody or other restricted units. Its informal synonym is genpop, a clipping of "general population". The noun gives rise to the verb for placing an inmate there, so an inmate who has been mainlined has been released into the mainline.
- 14The main pipe carrying wastewater from a building to the public sewers or a septic tank.
Wastewater from every fixture eventually drains into the mainline.
The crew replaced the old clay mainline with PVC pipe.
Note
Plumbers use it for the main drain that collects a building's branch lines and carries the flow off the property. Its most common partner is "connection": the mainline connection is where private drainage meets the public system, and often where a plumber's responsibility ends. It takes a regular plural, mainlines, and sits close to the shorter mains in technical writing on piping repair.
- 15In longline fishing, the central line to which the baited branch lines are attached.
Each baited snood clipped onto the mainline at regular intervals.
The boat set several miles of mainline before dawn.
Note
Longline fishing builds its gear around a single long backbone. The baited branch lines, called snoods, are clipped to it at intervals, and the whole rig can stretch for miles. Fishers speak of setting and hauling the mainline. It is the line itself, not the fishery, so a longliner sets mainline much as a farmer lays fence.
- 16Alternative form of main line.
The mainline of the Italian Game leads to sharp tactical play.
Commentators expected the mainline, but he chose a sideline instead.
Note
The closed spelling of the chess noun, as in Malcolm Pein's Daily Telegraph column of 2005: "...Qe7! is the mainline". Dictionaries cross-refer the two spellings in both directions, so neither is wrong. Main line is the open form, and the single word matches the adjective, which is how chess writers use it before a noun. In prose, pick one spelling and keep to it.
Showing meanings only.
Practice
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Origin
Formed by combining "main" and "line."