mainlined; mainlining; mainlines
slang
: to take by or as if by injecting into a principal vein
slang
: to mainline a narcotic drug
: being part of an established group
also
: being in the mainstream
1
: a principal highway or railroad line
2
slang
: a principal vein of the circulatory system
Examples of mainline in a Sentence
Verb
His addiction grew worse when he began mainlining.
Recent Examples on the Web
Erin Qualey, Vulture, 6 Mar. 2024
With a month or so in which to mainline asparagus, there’s no need to worry about tomatoes or zucchini.
—Yotam Ottolenghi, New York Times, 10 Apr. 2024
Zach Wichter, USA TODAY, 18 June 2024
Today, church membership is in decline, and the institutional influence of mainline protestant churches is much diminished (although to exactly what effect is debatable).
—Laura Bullard, Vox, 14 May 2024
Andrea Klick, Kansas City Star, 3 July 2024
This group, known as Hayat Tahrir al-Sham (HTS), now administers a swath of territory in Syria’s northwest and has tense relations, at best, with al Qaeda’s main line.
—Cole Bunzel, Foreign Affairs, 11 Feb. 2021
See all Example Sentences for mainline 
Verb
He’s stopped taking his pills and started mainlining cheap beer.
—Erin Qualey, Vulture, 6 Mar. 2024
With a month or so in which to mainline asparagus, there’s no need to worry about tomatoes or zucchini.
—Yotam Ottolenghi, New York Times, 10 Apr. 2024
Adjective
Most mainline Airbus and Boeing jets can take off safely up to 122 degrees or so.
—Zach Wichter, USA TODAY, 18 June 2024
Today, church membership is in decline, and the institutional influence of mainline protestant churches is much diminished (although to exactly what effect is debatable).
—Laura Bullard, Vox, 14 May 2024
Noun
Evergy crews are working to restore power and will first work to restore main lines that impact emergency services or a large amount of customers, the utility said in a statement Tuesday night.
—Andrea Klick, Kansas City Star, 3 July 2024
This group, known as Hayat Tahrir al-Sham (HTS), now administers a swath of territory in Syria’s northwest and has tense relations, at best, with al Qaeda’s main line.
—Cole Bunzel, Foreign Affairs, 11 Feb. 2021
See all Example Sentences for mainline
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'mainline.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
Dictionary Entries Near mainline
Cite this Entry
“Mainline.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mainline. Accessed 15 Jul. 2024.
Copy CitationMedical Definition
mainline
1 of 2 verb
main·line
ˈmān-ˈlīn 
mainlined; mainlining
slang
: to take by or as if by injecting into a principal vein
slang
: to mainline a narcotic drug (as heroin)
main line
2 of 2 noun
slang
: a principal vein of the circulatory system
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