centerline

[sen-ter-lahyn]

noun

any line that bisects a plane figure: the centerline of a building plan.
a line along the center of a road or highway dividing it into separate sections for traffic moving in opposite directions.
Radio. the perpendicular bisector of the line connecting two radio transmitters.

Origin of centerline

First recorded in 1800–10; center + line¹

The check valves are placed slightly below the centerline of the boiler (fig. 18).
Smithsonian Institution - United States National Museum - Bulletin 240
Anonymous
The opposing surface is not flat, but slopes away from the centerline like a boat's bow.
Following the Equator, Complete
Mark Twain (Samuel Clemens)
Daoud climbed a ladder, raised the heavy door, and found himself on a walkway built over the centerline of a roof.
The Saracen: Land of the Infidel
Robert Shea
The check valves are placed slightly below the centerline of the boiler (fig. 18).
The 'Pioneer': Light Passenger Locomotive of 1851
John H. White
A single leeboard was fitted and secured to the hull with a short piece of line made fast to the centerline of the boat.
The Migrations of an American Boat Type
Howard I. Chapelle