mainline

verb

main·​line ˈmān-ˌlīn 

mainlined; mainlining; mainlines

transitive verb

slang : to take by or as if by injecting into a principal vein

intransitive verb

slang : to mainline a narcotic drug

Examples of mainline in a Sentence

His addiction grew worse when he began mainlining.

Recent Examples on the Web

Start mainlining Centrum Silver, Boise. —Michael Deeds, Idaho Statesman, 10 Mar. 2026

Anderson’s composer, Jonny Greenwood (from Radiohead), alternates tones of wailing electronic despair and a pounding rhythm that mainlines energy. —David Denby, New Yorker, 9 Mar. 2026

Annie is alone, but things could be so much worse than spending your day reading in the Jungle Room and mainlining Bush’s Best; She’s tucked away safely and no one seems to bother her. —Maggie Fremont, Vulture, 23 Feb. 2026

Like the rest of the world, I’ve been glued to my couch this past weekend, mainlining season 4 of Bridgerton with a quickness. —Fleurine Tideman, Glamour, 2 Feb. 2026

Word History

First Known Use

1938, in the meaning defined at transitive sense

Rhymes for mainline

• affine
• airline
• align
• aline
• assign
• baseline
• beamline
• benign
• bloodline
• bovine
• brucine
• byline

Medical Definition

mainline

1 of 2 verb

main·​line ˈmān-ˈlīn 

mainlined; mainlining

transitive verb

slang : to take by or as if by injecting into a principal vein

intransitive verb

slang : to mainline a narcotic drug (as heroin)

main line

2 of 2 noun

slang

: a principal vein of the circulatory system