/mayn"luyn', -luyn"/ , v. , mainlined, mainlining , adj.
v.i. Slang.
1. to inject a narcotic, esp. heroin, directly into a vein.
2. to use or enjoy something without restriction: to mainline on TV movies.
v.t. Slang.
3. to inject (a narcotic, esp. heroin) directly into a vein.
4. to use, enjoy, or imbibe (something) without restriction: mainlining coffee all day long.
adj.
5. having a principal, established, or widely accepted position; major; mainstream: the membership of mainline churches.
[ 1935-40, Amer.; v., adj. use of MAIN LINE ]