| 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 fashionable residential district west of Philadelphia. |
| 2. | any fashionable district where socially prominent people live. |
| main line n.
|
Main Line  (mān')  A group of suburbs of southeast Pennsylvania. The fashionable area was named after the chief railroad line traveling west from Philadelphia. |