- noun the distance across the widest part of a circle or a tube
- The full width of a celestial object, measured either in units of distance or of angular measure as seen from the Earth or some other point
- noun the distance from one side of a circle to the other, passing through the centre
Cars & Driving
- noun the length of a straight line through the centre of a circular object connecting two directly opposite points on its circumference
- The line in a circle passing through its center. Also refers to the nominal diameter designated by an approved material standard.