Question

what is meant focus point​

Answer 1

In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge. A principal focus or focal point is a special focus: For a lens, or a spherical or parabolic mirror, it is a point onto which collimated light parallel to the axis is focused.

Answer 2

Answer:

(focus, focal point)

a point of convergence of light (or other radiation) or a point from which it diverges

OR

(focus, focal point)

a central point or locus of an infection in an organism