a principal line or route of a railroad, as contrasted with a branch or secondary one.
a principal highway.
Slang.
a prominent and readily accessible vein of the body that may be used for a narcotic's injection.
the act of mainlining.
a fashionable residential district west of Philadelphia.
any fashionable district where socially prominent people live.
railways
the trunk route between two points, usually fed by branch lines
( as modifier )
a main-line station
a main road
First recorded in 1835–45
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Lizzy Stroud and her husband Dave run self-catering accommodation in converted train carriages at stations on the Great Western Railway main line at St Germans and Harvey of Hayle, near St Ives in Cornwall.
From BBC ● May 8, 2026
Pike followed the main line — called the trunk line — which had hoses branching off in other directions.
From Los Angeles Times ● Mar. 11, 2026
A message The Associated Press left on the city’s Law Department main line seeking comment Monday wasn’t immediately returned.
From Seattle Times ● May 27, 2024
They are the ship's main line of defence.
From BBC ● Mar. 25, 2024
Railroad workers had laid a temporary track between the main line and the street so that the wagon could pull up next to the president's rail car.
From "Ambushed!" by Gail Jarrow
Network Rail has warned that the Midland Main Line will remain closed to East Midlands Railway and Thameslink services until the end of the week.
From BBC ● Jun. 24, 2026
In suburbs including Philadelphia’s Main Line, moms and dads are pleading with districts to rein in tech: “These electronics have ruined parenting.”
From The Wall Street Journal ● Jun. 22, 2026
Under current plans, HS2 trains will travel from Birmingham to Manchester, but at reduced speed on the existing West Coast Main Line.
From BBC ● Mar. 23, 2026
Cardinale grew up in Villanova, Penn., an affluent suburb on Philadelphia’s Main Line, and attended The Haverford School, an all-boys prep school.
From The Wall Street Journal ● Jan. 16, 2026
It’s on the prestigious Main Line, just twenty-five minutes outside Philadelphia, on a rolling campus surrounded by overgrown foliage.
From "The Other Wes Moore: One Name, Two Fates" by Wes Moore
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
