zhǔ​xiàn

main line

主线 (主線) zhǔ​xiàn
main line noun
main line of communication, transportation, or physical infrastructure

The main line of this highway has been fully connected.

main thread noun
central theme or primary plotline of a story or concept

The main plotline of this novel is very clear.

Frequency

Movie subtitles
0.540 per million appears in 0% of films
Written text
6.64 per million

Sources

Definitions
CC-CEDICT