trunk line

• Rhymes: -aɪn

trunk line (plural trunk lines)

1. (rail transport) A main railway line which usually forms the backbone of a rail network.

   Coordinate term: mainline

   • 1987, William H. Rehnquist, The Supreme Court:

     But the states were generally concerned with the location of trunk lines and left it to cities and counties to worry about branch lines.

2. The main line of a canal, from which other sections diverge.
3. A main telephone line.
   • 1943, H. Lorna Bingham, The Lost Tribe, Sydney: Winn and Co., page 13, column 2:

     Then he put a trunk line phone call through to the nearest township and asked the Police to send someone out as soon as possible.

• trunkline

• “trunk line”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.