An arc is a part of a circle that is defined by its endpoints. It is a segment of the circumference of the circle.
A chord or its radius
A chord is the part of a circle defined by two endpoints.
A ray
i think its the diameter
A circle. has no endpoints.
if you mean the point that starts at the edge of the circle and ends in the center then this is the radius (:
A chord is a line segment whose endpoints lie on a circle. A secant is a line (or line segment) that intersects a circle in two places, endpoints NOT on the circle.
it the circumference of a circle
It is a semicircular arc.
The line passing through the center of a circle with two endpoints on the circle is the circle's diameter.
The points where a diameter intersects the circle are its endpoints.