What is a chord in a circle?

A chord in a circle is defined as a segment whose endpoints both lie on the circle itself. This means that a chord connects two points that are part of the circle's boundary, effectively slicing through the interior. The properties of a chord include being shorter than a diameter and having the ability to create two distinct arcs on either side of it within the circle.

Other options describe different geometric concepts: a segment lying outside the circle does not interact with the circle's boundary; a segment from the circle’s center to a point on the circle is known as a radius; and a segment that is tangent to the circle touches the circle at precisely one point but does not cross into the circle itself. Thus, the definition provided in the correct choice accurately describes what a chord is.