mainline
Americanverb (used without object)
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to inject a narcotic, especially heroin, directly into a vein.
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to use or enjoy something without restriction.
to mainline on TV movies.
verb (used with object)
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to inject (a narcotic, especially heroin) directly into a vein.
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to use, enjoy, or imbibe (something) without restriction.
mainlining coffee all day long.
adjective
Etymology
Origin of mainline
1935–40, v., adj. use of main line
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The 04:28 Avanti West Coast service came off the tracks on the West Coast mainline at Shap in Cumbria on Monday morning after travelling at speeds of 80mph.
From BBC • Nov. 4, 2025
Relatives of the inmates’ victims are divided over altering regulations to ensure the convicts go to Florence, rather than to the mainline prisons their disciplinary records called for.
From The Wall Street Journal • Oct. 11, 2025
With that guidance, officials canceled plans to transfer most of the inmates to mainline prisons.
From The Wall Street Journal • Oct. 11, 2025
He used to present as a staid mainline Episcopalian, but now he denounces that church and speaks of being “mauled by demons.”
From Salon • May 19, 2025
Black Muslims came in many stripes, from mainline Nation of Islam to the splinter Five Percenters.
From "Newjack: Guarding Sing Sing" by Ted Conover
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
