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
Other Word Forms
Conjugated Forms
Present
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has mainlinedperfect 3rd person singular
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have mainlinedperfect
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has been mainliningperfect progressive 3rd person singular
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have been mainliningperfect progressive
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are mainliningprogressive
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is mainliningprogressive 3rd person singular
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mainlinessingular 3rd person
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am mainliningprogressive 1st person singular
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mainliningparticiple
Past
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had mainlinedperfect
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had been mainliningperfect progressive
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was mainliningprogressive singular
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mainlinedsimple
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mainlinedparticiple
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were mainliningprogressive plural
Future
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 game will launch on current-generation consoles, PC and Nintendo Switch 2, marking the first mainline Call of Duty to skip PlayStation 4 and Xbox One.
From BBC • May 29, 2026
“We’ve made it kind of core to who Allegiant is to seek out opportunities that aren’t typically served by mainline carriers,” said Drew Wells, the airline’s chief commercial officer.
From The Wall Street Journal • May 17, 2026
The service has been installed on regional jets and United says it will be on 50% of its mainline fleet by the end of the year and 100% next year.
From The Wall Street Journal • Apr. 25, 2026
There had been nothing going out on the West Coast mainline and hardly any announcements, she said.
From BBC • Nov. 21, 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.
