A secant can be described as:

A secant line is defined as a line that intersects a circle at exactly two points. This definition is foundational in understanding circular geometry, as it helps to differentiate secants from tangents and other types of lines associated with circles. In the context of circles, the secant is crucial because it provides a way to explore properties like chords and areas formed within the circle.

The other options refer to different concepts within circle geometry: a line passing through the center and two points would describe a diameter; a line tangent to the circle touches the circle at exactly one point; and a line that only intersects one point of the circle describes a tangent as well. By focusing on the specific property of intersecting at two distinct points, we clarify the unique role that secant lines play in geometric constructions and theorems.