(A) In Geometry, an intersection is a single
point where two lines or curves meet or cross each other.

In the figure above, point K is the intersection
of line segments AB and CD.

Another way it may be said is that the line
segment CD intersects AB at point K.

(B)In set theory,an intersection of two sets
A and B is the set that contains all elements of A that also
belong to B (or equivalently, all elements of B that also
belong to A), but no other elements.