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
Jack King, Vulture, 13 Oct. 2024
The season is long, and cold, and involves a lot of staying in bed on your laptop until 1 pm and also mainlining Oreos while half-watching The Holiday on your mum’s sofa and scrolling Instagram.
—Daisy Jones, Vogue, 22 Oct. 2024
Yeo Boon Ping, CNBC, 20 Feb. 2025
Regional airline crews also are held to the same high training standards and minimum flight hours as mainline aviators, although because of the higher pay scales at mainline carriers, regional airlines often hire pilots that are newer to the industry.
—Zach Wichter, USA TODAY, 20 Feb. 2025
Gary Warth, San Diego Union-Tribune, 19 Feb. 2025
The brand’s main line, which marries accessible luxury with a European flair, is priced between $149 to $1,295.
—Evan Clark, WWD, 13 Feb. 2025
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
For the guys below the line — not least poor Daniel, who spends his drive to work mainlining his vape while listening to a woefully inadequate meditation tape — there’s existential terror in the air apropos of the arrival of new producer Anita at the end of episode one.
—Jack King, Vulture, 13 Oct. 2024
The season is long, and cold, and involves a lot of staying in bed on your laptop until 1 pm and also mainlining Oreos while half-watching The Holiday on your mum’s sofa and scrolling Instagram.
—Daisy Jones, Vogue, 22 Oct. 2024
Adjective
Apple drops new iPhone Apple announced on Wednesday the iPhone 16e, which is priced at $599, lower than its mainline iPhone models, and will go on sale later this month.
—Yeo Boon Ping, CNBC, 20 Feb. 2025
Regional airline crews also are held to the same high training standards and minimum flight hours as mainline aviators, although because of the higher pay scales at mainline carriers, regional airlines often hire pilots that are newer to the industry.
—Zach Wichter, USA TODAY, 20 Feb. 2025
Noun
As explained by Padre Dam Municipal Water District CEO and General Manager Kyle Swanson, a significant part of the cost increase is for the rehabilitation of the 8-mile, 48-inch East Mission Gorge force main line, including a long stretch through Mission Trails Regional Park.
—Gary Warth, San Diego Union-Tribune, 19 Feb. 2025
The brand’s main line, which marries accessible luxury with a European flair, is priced between $149 to $1,295.
—Evan Clark, WWD, 13 Feb. 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 22 Mar. 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
Love words? Need even more definitions?
Merriam-Webster unabridged
Share