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
Charlie Warzel, The Atlantic, 13 June 2025
It ideally should be mainlined, er, consumed in its purest right-out-of the-jar form.
—Inga, San Diego Union-Tribune, 28 Apr. 2025
Ewan Spence, Forbes.com, 27 June 2025
The number of Catholics is roughly double the number of the mainline Protestants who once dominated America’s public life.
—Chris Stirewalt, The Hill, 9 May 2025
Vinod Sreeharsha, Miami Herald, 21 June 2025
In terms of devices, Google looks to be settled on a main line of the Pixel and Pixel Pro smartphones (with Pro and Pro XL models) in Q3, and the mid-range Pixel A Series in Q1.
—Ewan Spence, Forbes.com, 11 Apr. 2025
See All Example Sentences for mainline
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Verb
The distortions are everywhere: People mainlining fascistic AI slop are occupying an alternate reality.
—Charlie Warzel, The Atlantic, 13 June 2025
It ideally should be mainlined, er, consumed in its purest right-out-of the-jar form.
—Inga, San Diego Union-Tribune, 28 Apr. 2025
Adjective
Notable for its modularity and ease of repair, the company is bringing that to the fore with the sixth mainline model.
—Ewan Spence, Forbes.com, 27 June 2025
The number of Catholics is roughly double the number of the mainline Protestants who once dominated America’s public life.
—Chris Stirewalt, The Hill, 9 May 2025
Noun
Smart switches can go on main lines or neighborhood power lines.
—Vinod Sreeharsha, Miami Herald, 21 June 2025
In terms of devices, Google looks to be settled on a main line of the Pixel and Pixel Pro smartphones (with Pro and Pro XL models) in Q3, and the mid-range Pixel A Series in Q1.
—Ewan Spence, Forbes.com, 11 Apr. 2025
See All Example Sentences for mainline
Cite this Entry
“Mainline.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mainline. Accessed 2 Jul. 2025.
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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