In general terms, a centerline is a real or imaginary line that passes through the center of something, often dividing the object into two equal halves and creating a mirror-like reflection on either side.
- In a wave diagram used to illustrate electromagnetic waves, a centreline may be used to show either:
- The point where the electric and magnetic fields intersect, so illustrating the axis along which a wave propagates.
- A point located halfway between the crest and trough of a wave, illustrating the axis along which a wave propagates.