main line

1. 1.

   the principal route of a transportation system

   Broaderpath

Questions about main line

What does main line mean?

main line means "the principal route of a transportation system".

Is main line a common word?

main line is banded "Uncommon" — turns up in careful writing rather than conversation. The band comes from how often the word appears in a large corpus of everyday English, not from an editor's impression.