main line

¹ American  

noun

1. a principal line or route of a railroad, as contrasted with a branch or secondary one.

2. a principal highway.

3. Slang.

   1. a prominent and readily accessible vein of the body that may be used for a narcotic's injection.

   2. the act of mainlining.

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Main Line ² American  

noun

1. a fashionable residential district west of Philadelphia.

2. any fashionable district where socially prominent people live.

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main line British  

noun

1. railways

   1. the trunk route between two points, usually fed by branch lines

   2. ( as modifier )

      a main-line station

2. a main road

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verb

1. slang (intr) to inject a drug into a vein

adjective

1. having an important position, esp having responsibility for the main areas of activity

Other Word Forms

• Main-Line adjective
• Main-Liner noun
• mainliner noun

Etymology

Origin of main line

First recorded in 1835–45

Example Sentences

Pike followed the main line — called the trunk line — which had hoses branching off in other directions.

From Los Angeles Times • Mar. 11, 2026

They are the ship's main line of defence.

From BBC • Mar. 25, 2024

Currently, the underground railway’s main line winds from northeastern China to southwestern Yunnan province and into Southeast Asia.

From Washington Times • Nov. 22, 2023

It’s also his main line of communication to two of his children, who are students at the University of Southern California.

From Seattle Times • Nov. 17, 2023

This divide-and-conquer strategy is better than repeatedly allowing counterexamples to intrude into the main line of an argument while browbeating readers into looking away.

From "The Sense of Style" by Steven Pinker

Related Words

• affluent
• booming
• comfortable
• flourishing
• fortunate
• rich
• robust
• wealthy
• well-heeled
• well-off
• well-to-do