1. a real or imaginary line that runs through the center of something, dividing it into two equal parts
2. the painted line down the middle of a road that separates traffic going in opposite directions

Examples

• The pilot kept the aircraft on the runway centerline during takeoff.
• Never cross the centerline when driving on a two-lane highway.
• The architect drew a centerline through the building’s floor plan.
• The yellow centerline divides the road into two lanes.
• She measured from the centerline to ensure the design was symmetrical.
• The ship’s centerline runs from bow to stern.
• Traffic cones marked the centerline of the construction zone.