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
Michael Deeds, Idaho Statesman, 10 Mar. 2026 Anderson’s composer, Jonny Greenwood (from Radiohead), alternates tones of wailing electronic despair and a pounding rhythm that mainlines energy. —David Denby, New Yorker, 9 Mar. 2026
Chris Roemer, Baltimore Sun, 2 Apr. 2026 In 2017, about 27% of pastors in mainline Protestant churches were women, including, but not limited to, those in senior positions. —Mary Foskett, The Conversation, 20 Mar. 2026
Doug Ross, Chicago Tribune, 5 Apr. 2026 As far as a solution to our big number two problem, there are two main lines of thinking. —Andrew Paul, Popular Science, 25 Mar. 2026 See All Example Sentences for mainline
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Verb
Start mainlining Centrum Silver, Boise. —Michael Deeds, Idaho Statesman, 10 Mar. 2026 Anderson’s composer, Jonny Greenwood (from Radiohead), alternates tones of wailing electronic despair and a pounding rhythm that mainlines energy. —David Denby, New Yorker, 9 Mar. 2026
Adjective
Indeed, according to the 2025 National Survey of Religious Leaders, only 65% of current mainline pastors believe in something as fundamental to the Christian faith as the bodily resurrection of Christ. —Chris Roemer, Baltimore Sun, 2 Apr. 2026 In 2017, about 27% of pastors in mainline Protestant churches were women, including, but not limited to, those in senior positions. —Mary Foskett, The Conversation, 20 Mar. 2026
Noun
Construction has finally started for the trail to go under the Norfolk Southern main line. —Doug Ross, Chicago Tribune, 5 Apr. 2026 As far as a solution to our big number two problem, there are two main lines of thinking. —Andrew Paul, Popular Science, 25 Mar. 2026 See All Example Sentences for mainline
Cite this Entry
“Mainline.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.grautoblog.com/dictionary/mainline. Accessed 27 Apr. 2026.
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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