mainline

[meyn-lahyn, -lahyn]

to inject a narcotic, especially heroin, directly into a vein.

to use or enjoy something without restriction: to mainline on TV movies.

to inject (a narcotic, especially heroin) directly into a vein.

to use, enjoy, or imbibe (something) without restriction: mainlining coffee all day long.

having a principal, established, or widely accepted position; major; mainstream: the membership of mainline churches.

Origin of mainline

1935–40, Americanism; v., adj. use of main line

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

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Word Origin and History for mainlining

also main-line, 1934, from main line in American English slang sense "principal vein into which drugs can be injected" (1933).