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
Inflected Forms
Participles
Conjugated Forms
Present
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mainlinesimple
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mainlinessimple
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have mainlinedperfect
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has mainlinedperfect
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am mainliningprogressive
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are mainliningprogressive
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is mainliningprogressive
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have been mainliningperfect progressive
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has been mainliningperfect progressive
Past
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mainlinedsimple
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had mainlinedperfect
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was mainliningprogressive
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were mainliningprogressive
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had been mainliningperfect progressive
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.
Located above a busy mainline railway station, MSG is slap bang in the beating heart of tourist and commercial Manhattan.
From Barron's • Jul. 1, 2026
The mainline is a collection of long-established Protestant denominations: the Episcopalians, United Methodists, Presbyterians and so on.
From The Wall Street Journal • Jun. 25, 2026
The news has sparked excitement and discussion among fans, particularly around the next mainline entry starring a woman.
From BBC • Jun. 3, 2026
The airline’s cancellations related to pilot availability are more than 10 times historical levels, and account for 35% of its mainline flight cancellations.
From The Wall Street Journal • May 26, 2026
Like many other evangelicals, some members attend churches that adhere to evangelical doctrine but that remain affiliated with mainline 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.
