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.
It could have come to life as a lesser kind of Ferrari, a diminished derivative of one of the company’s mainline GT cars, with a turbocharged V8 under the hood.
From The Wall Street Journal • Apr. 18, 2026
The genius of hit songs, beyond technical artistry—and the vagaries of timing—is the ability to mainline emotion.
From The Wall Street Journal • Mar. 5, 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
In the 2025 spending review, the Department of Transport secured £41m to introduce low earth orbit satellite connectivity on all mainline trains by 2030.
From BBC • Nov. 16, 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.
