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

The working-out of that vision, by way of experience that arises from her sudden change of circumstances, is the movie’s emotional and intellectual heart, its main line, abstract in form but altogether concrete in the decisions that result. — Richard Brody, New Yorker, 19 Aug. 2026

There are about 547 miles of trunk line underground across the city and 6,780 miles of distribution pipes, or main lines, in Los Angeles. — Hannah Fry, Los Angeles Times, 25 July 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