mainline
Americanverb (used without object)
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to inject a narcotic, especially heroin, directly into a vein.
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to use or enjoy something without restriction.
to mainline on TV movies.
verb (used with object)
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to inject (a narcotic, especially heroin) directly into a vein.
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to use, enjoy, or imbibe (something) without restriction.
mainlining coffee all day long.
adjective
Other Word Forms
Inflected Forms
Participles
Conjugated Forms
Present
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mainlinesimple
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mainlinessimple
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have mainlinedperfect
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has mainlinedperfect
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am mainliningprogressive
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are mainliningprogressive
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is mainliningprogressive
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have been mainliningperfect progressive
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has been mainliningperfect progressive
Past
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mainlinedsimple
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had mainlinedperfect
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was mainliningprogressive
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were mainliningprogressive
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had been mainliningperfect progressive
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
The mainline is a collection of long-established Protestant denominations: the Episcopalians, United Methodists, Presbyterians and so on.
From The Wall Street Journal ● Jun. 25, 2026
Given that the bulk of mainline members and leaders are elderly, a grassroots insurgency makes sense.
From The Wall Street Journal ● Jun. 25, 2026
Like many other evangelicals, some members attend churches that adhere to evangelical doctrine but that remain affiliated with mainline denominations.
From "Class Matters" by The New York Times
Trunk lines appear to be in better condition than the utility’s mainlines.
From Los Angeles Times ● Jul. 25, 2026
He mainlines all of his romantic entanglements as if they were the antidote to his unresolved traumas.
From Salon ● Apr. 25, 2025
Current labor agreements ensure that freight trains on mainlines have two people — an engineer and conductor — onboard.
From Washington Post ● Mar. 3, 2023
Investigators said testing found that the gas lines between the home’s meter and the mainlines of the local utility, CenterPoint Energy, were in “proper working order.”
From Seattle Times ● Nov. 2, 2022
Other operators will also run some trains on the east coast and west coast mainlines.
From BBC ● Jun. 15, 2022
We’ve gladly plugged ourselves into virtual reality headsets, and we’ve mainlined our personal preferences and purchasing tendencies into Silicon Valley’s fat veins.
From Los Angeles Times ● Feb. 24, 2023
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
I mean, they’re really being mainlined right into your brain.
From Washington Post ● Oct. 15, 2018
He mainlined fantasy, horror, science fiction and drama growing up, and started as a fanboy.
From New York Times ● Oct. 20, 2016
It is less a video game than mainlined anxiety, its jump-scares timed with sadistic precision and its long, shadow-splashed corridors masterpieces of unnerving light design.
From Slate ● Feb. 1, 2011
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
Last month, she lamented that her busy campaign schedule had kept her from mainlining Amazon’s new “Rings of Power” series.
From New York Times ● Sep. 21, 2022
‘Ready Player One’ feels like mainlining the VH1 show ‘I Love the ’80s.’
From Washington Post ● Jul. 14, 2021
Youths, I am told, speak of “hopium” and “copium,” but we need a word that incorporates the never-ending mainlining of information as well as the positive or negative cast of that information.
From Slate ● Nov. 6, 2020
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
