Which undefined term is used to define an angle

The  undefined term that is used to define an angle is:

                            Line.

Angle is formed with the help of two lines which are not parallel to each other and intersect at a point.

( Also, such two lines are known as a ray.

Since a ray is a line with one end point and the angle is formed with the help of 2 rays with the same starting or initial point  )

From the diagram we may see how the angle is formed.

                   Hence, the answer is:

                          Line

Line

Step-by-step explanation:

A line is a undefined term used to define a angle. An angle is the corner that is created where two non-parallel lines meet/ intersect