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 train operator LNER, which runs the east coast mainline, has extended its advice to passengers not to travel between Edinburgh and Aberdeen as they "cannot guarantee" trains will operate until Friday at the earliest.
From BBC • Jan. 6, 2026
The tax burden would be disproportionately felt by progressive mainline Protestant churches, Black evangelical churches and immigrant-majority Catholic and Protestant congregations, not to mention immigrant-majority mosques and temples.
From Salon • Nov. 16, 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
On being told of Tilly’s existence by an interviewer for Variety, “Please stop,” she insisted, while demanding that mainline studios and talent agencies refrain from trafficking with AI actresses.
From The Wall Street Journal • Oct. 10, 2025
But over the last forty years, evangelicals have pulled steadily closer in income and education to mainline Protestants in the historically affluent establishment denominations.
From "Class Matters" by The New York Times
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.
