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
Joe Hindy, PCMAG, 19 Feb. 2025
About 67% of US airports are served only by regional airlines, according to the RAA, while its data shows the mainline operations of airlines using full-size jets only reach 37% of US airports.
—Chris Isidore, CNN, 18 Feb. 2025
Evan Clark, WWD, 13 Feb. 2025
Pumps forcibly move water from main lines and surrounding reservoirs to those tanks.
—Katie Tarasov, CNBC, 30 Jan. 2025
See All Example Sentences for mainline
Examples are automatically compiled from online sources to
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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
Per MacRumors, Apple has never discontinued a mainline iPhone in the middle of a release cycle like this.
—Joe Hindy, PCMAG, 19 Feb. 2025
About 67% of US airports are served only by regional airlines, according to the RAA, while its data shows the mainline operations of airlines using full-size jets only reach 37% of US airports.
—Chris Isidore, CNN, 18 Feb. 2025
Noun
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
Pumps forcibly move water from main lines and surrounding reservoirs to those tanks.
—Katie Tarasov, CNBC, 30 Jan. 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 4 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
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