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
Daisy Jones, Vogue, 22 Oct. 2024
Charismatic Christians, however, are affiliated with other denominations, from Catholicism to mainline Protestant churches.
—Dara Delgado, The Conversation, 3 Oct. 2024
Sophie Carson, Journal Sentinel, 4 Nov. 2024
Most mainline Christian denominations affirm gay and lesbian people.
—John Blake, CNN, 3 Nov. 2024
Kubie Brown, Outdoor Life, 3 Oct. 2024
The debate comes as Walz and the Harris campaign have used Project 2025 as a main line of attack against Trump and Vance, holding its extreme proposals up as a key reason for voters to oppose Trump’s candidacy.
—Alison Durkee, Forbes, 1 Oct. 2024
See all Example Sentences for mainline 
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Verb
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
Charismatic Christians, however, are affiliated with other denominations, from Catholicism to mainline Protestant churches.
—Dara Delgado, The Conversation, 3 Oct. 2024
Adjective
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
Most mainline Christian denominations affirm gay and lesbian people.
—John Blake, CNN, 3 Nov. 2024
Noun
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
The debate comes as Walz and the Harris campaign have used Project 2025 as a main line of attack against Trump and Vance, holding its extreme proposals up as a key reason for voters to oppose Trump’s candidacy.
—Alison Durkee, Forbes, 1 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 14 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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