mainline

1 of 3

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

mainline

2 of 3

adjective

: being part of an established group

also : being in the mainstream

main line

3 of 3

noun

1

: a principal highway or railroad line

2

slang : a principal vein of the circulatory system

Examples of mainline in a Sentence

Verb

His addiction grew worse when he began mainlining.

Recent Examples on the Web

Verb

This era of Jane Remover—the music, which mainlines the noisiest impulses of SounDC, the discourse—is brasher and more acidic than ever. — Mano Sundaresan, Pitchfork, 10 June 2026

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

Adjective

Doom comes from the Fantastic Four’s universe, Earth-828, rather than the mainline Marvel Cinematic Universe. — Wesley Stenzel, Entertainment Weekly, 26 July 2026

Sutton points to, among other factors, a gap between the progressive stances adopted by mainline clergy and the more conservative views of the average mainline churchgoer. — Michael Luo, New Yorker, 14 June 2026

Noun

Techno and dance music were blaring throughout the space next to the San Diego Bay, with separate lines (after the big main line) once participants got inside. — Phillip Molnar, San Diego Union-Tribune, 24 July 2026

Higher prices are not Apple’s main line of defence against revenue losses. — Ewan Spence, Forbes.com, 27 June 2026

Word History

First Known Use

Verb

1938, in the meaning defined at transitive sense

Adjective

1941, in the meaning defined above

Noun

1841, in the meaning defined at sense 1

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