verb (used without object), main·lined, main·lin·ing. Slang.
to inject a narcotic, especially heroin, directly into a vein.
to use or enjoy something without restriction: to mainline on TV movies.
verb (used with object), main·lined, main·lin·ing. Slang.
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
Examples from the Web for mainlining
Contemporary Examples of mainlining
Or was he "mainlining the secret truth of the universe" again?‘True Detective’ Finale Review: Close to Perfection
March 10, 2014
also main-line, 1934, from main line in American English slang sense "principal vein into which drugs can be injected" (1933).
Online Etymology Dictionary, © 2010 Douglas Harper