What.

a line segment whose endpoints lie on a circle.

a line that intersects a circle at exactly two points.

a line that intersects a circle at exactly one point.

a chord that passes through the center of a circle.

a line segment with one endpoint at the center of a circle and the other endpoint on the circle.

a portion of a circle.

an angle whose vertex is at the center of a circle and whose sides pass through a pair of points on the circle.

an angle formed when two chords, two secant lines, or a secant and tangent line, intersect at a point on a circle.

the portion of a circle that lies between two lines, rays, or line segments that intersect the circle.

An arc of a circle measuring more than or equal to 180.