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Synonyms

mainline

American  
[meyn-lahyn, -lahyn] / ˈmeɪnˌlaɪn, -ˈlaɪn /

verb (used without object)

Slang.
  • mainlines,
    present (3rd person singular)
  • mainlined,
    past participle,  past
  • mainlining
    present participle
  1. to inject a narcotic, especially heroin, directly into a vein.

  2. to use or enjoy something without restriction.

    to mainline on TV movies.


verb (used with object)

Slang.
  • mainlines,
    present (3rd person singular)
  • mainlined,
    past participle,  past
  • mainlining
    present participle
  1. to inject (a narcotic, especially heroin) directly into a vein.

  2. to use, enjoy, or imbibe (something) without restriction.

    mainlining coffee all day long.

adjective

  1. having a principal, established, or widely accepted position; major; mainstream.

    the membership of mainline churches.

Other Word Forms

Inflected Forms

Participles

Conjugated Forms

Present

Past

Future

Etymology

Origin of mainline

1935–40, v., adj. use of main line

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

DWP plans to replace about 45 miles of mainline, which deliver water to individual services across neighborhoods, this fiscal year.

From Los Angeles Times Jul. 25, 2026

Located above a busy mainline railway station, MSG is slap bang in the beating heart of tourist and commercial Manhattan.

From Barron's Jul. 1, 2026

That, combined with the demographics of the mainline, makes some success seem inevitable.

From The Wall Street Journal Jun. 25, 2026

The game will launch on current-generation consoles, PC and Nintendo Switch 2, marking the first mainline Call of Duty to skip PlayStation 4 and Xbox One.

From BBC May 29, 2026

But over the last forty years, evangelicals have pulled steadily closer in income and education to mainline Protestants in the historically affluent establishment denominations.

From "Class Matters" by The New York Times

Thursday’s fracture was on a riveted steel pipe from 1916 that is part of the system of major arteries that deliver water from reservoirs and tanks to smaller distribution mainlines across Los Angeles.

From Los Angeles Times Jul. 20, 2026

He mainlines all of his romantic entanglements as if they were the antidote to his unresolved traumas.

From Salon Apr. 25, 2025

Afterward, Healey said the agency was underestimating the blockages on Westlake, including relocation of two sewer mainlines.

From Seattle Times Jul. 28, 2023

Current labor agreements ensure that freight trains on mainlines have two people — an engineer and conductor — onboard.

From Washington Post Mar. 3, 2023

Trains in England and Wales will also be badly affected, including services between London and Scotland on both the East and West Coast mainlines.

From BBC Jun. 18, 2022

Johnson said that businesses had mainlined on low-wage imported labour for nearly 25 years and that they should now pay their workers more and invest more.

From Reuters Oct. 5, 2021

“Hades,” because you can really get in the zone on that game, and they’ve got the meta-upgrade drug mainlined right to your brain: So.

From Los Angeles Times May 5, 2020

In 10 weeks as an editing intern, I mainlined more plays, musicals, ballets and cabaret performances than many people see in their entire lives.

From New York Times Aug. 28, 2019

All of that is mainlined into her songs.

From Slate Mar. 29, 2019

I mean, they’re really being mainlined right into your brain.

From Washington Post Oct. 15, 2018

The ubiquity of holiday songs also represents a rare monocultural music moment—even though listeners are spread across multiple streaming services and social-media platforms, many of them are mainlining the same tunes.

From The Wall Street Journal Dec. 14, 2025

In some ways, I feel like a conspiracy junkie who has relapsed, mainlining paranoia and dread.

From Salon Jul. 17, 2024

Most of the time, if you’re on Twitter, you’re doing something else or mainlining information before leaving.

From Slate Apr. 13, 2023

He was mainlining applause from the public gallery.

From Washington Post Jul. 8, 2022

She has been riding out the pandemic in a tiny village on an Irish mountaintop, watching murder shows, buying fairy-garden trinkets online and mainlining American news on CNN.

From New York Times May 18, 2021

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