What is the name of a chord that passes through the center of a circle?

A chord that passes through the center of a circle is specifically called a diameter. The diameter is the longest possible chord in a circle, spanning from one side of the circle to the other and intersecting at the center. This property defines the diameter, making it a crucial concept in geometry related to circles.

A radius, while related to circles, is the line segment that connects the center of the circle to any point on its circumference, and it is not a chord since it does not connect two points on the circle directly across from each other. A chord is a line segment that connects two points on the circumference of the circle, but it does not necessarily pass through the center. An arc is a portion of the circumference of the circle and does not refer to a line segment at all. Thus, the term 'diameter' accurately identifies the chord that meets the specified criteria in the question.