If it connects the center of the circle to the edge, it is the radius. If it is a straight line that connects the edges of a circle through the center, it is the diameter.
The segment you describe is the radius of the circle.
Such a line segment would be a radius of the circle.
The line segment is a radius.
diameter
radius
The radius goes from the center out to the edge of the circle.
A radius.
Is called a radius.
The answer depends on where the other end of the line segment is. If it is on the circumference the segment is a radius. Otherwise, it is indeterminate.
The radius of a circle connects its center to its circumference.
The line segment is the radius of a circle that connects the center of a circle to any point on its circumference.
A line segment with the center of a circle as one endpoint and the other endpoint on the circumference of the circle is a rdius of that circle.