The point on a concave mirror's optical axis through which every light ray traveling parallel to the axis converges after reflection is called the focal point or focus.

Here's why:

* Concave mirrors converge light: Concave mirrors have a curved inward shape that causes parallel light rays to converge at a single point.

* Focal point definition: The focal point is the point where these converging light rays intersect.

* Optical axis: The optical axis is an imaginary line passing through the center of the mirror's curvature and perpendicular to the mirror's surface.

Therefore, any light ray traveling parallel to the optical axis of a concave mirror will be reflected and pass through the focal point.