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
Cade Onder, Rolling Stone, 25 Oct. 2024
Almost all mainline Christian faiths have seen precipitous drops in the pews, but the smaller presence of Catholicism is particularly evident in Milwaukee, where Catholic churches historically have anchored neighborhoods and acted as virtual community centers.
—Sophie Carson, Journal Sentinel, 4 Nov. 2024
Joe Cermele, Outdoor Life, 17 Oct. 2024
Set it up by tying a 12 to 24 inch length of 6-lb fluorocarbon to your main line, leaving a 3- to 4-inch tag end off your knot, and then tie on a 1/4 ounce casting weight to the bottom of the line.
—Kubie Brown, Outdoor Life, 3 Oct. 2024
See all Example Sentences for mainline 
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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
Both the mainline entries and Warzone are iterating upon each other as Warzone takes on mechanical innovations such as movement changes while titles like Modern Warfare III have utilized the battle royale’s maps and armor system within their campaigns.
—Cade Onder, Rolling Stone, 25 Oct. 2024
Almost all mainline Christian faiths have seen precipitous drops in the pews, but the smaller presence of Catholicism is particularly evident in Milwaukee, where Catholic churches historically have anchored neighborhoods and acted as virtual community centers.
—Sophie Carson, Journal Sentinel, 4 Nov. 2024
Noun
To avoid line twist and fouling, add a barrel swivel between your main line and leader when fishing a Krocodile.
—Joe Cermele, Outdoor Life, 17 Oct. 2024
Set it up by tying a 12 to 24 inch length of 6-lb fluorocarbon to your main line, leaving a 3- to 4-inch tag end off your knot, and then tie on a 1/4 ounce casting weight to the bottom of the line.
—Kubie Brown, Outdoor Life, 3 Oct. 2024
See all Example Sentences for mainline
Dictionary Entries Near mainline
Cite this Entry
“Mainline.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mainline. Accessed 21 Nov. 2024.
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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