The Probert Encyclopaedia of Science & Technology

DIAMETER

Diameter is the straight line drawn through the centre of a circle, and touching the two opposite points of the circumference. It thus divides the circle into two equal parts, and is the greatest chord. The length of the diameter is to the length of the circumference of the circle as 1 to 3.14159265..., the latter number being an interminable decimal.
Research Diameter