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
Glenn Taylor, Sourcing Journal, 9 July 2025
There were mainline protestants, Catholics, Muslims, and Jews involved — but only a handful of evangelicals.
—Sophie Hartley, IndyStar, 2 July 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
Since Monday, the inclement weather has prevented feeder vessels from collecting cargo from larger, mainline vessels anchored at sea and transporting it through the country’s waterways.
—Glenn Taylor, Sourcing Journal, 9 July 2025
There were mainline protestants, Catholics, Muslims, and Jews involved — but only a handful of evangelicals.
—Sophie Hartley, IndyStar, 2 July 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 23 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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