- a straight line passing through the center of a circle or sphere and meeting the circumference or surface at each end.
- a straight line passing from side to side of any figure or body, through its center.
Origin of diameter
Examples from the Web for diameter
Kepler-186f is about 11 percent larger than Earth in diameter, which means it has nearly 25% more surface area.What Does the Discovery of “Another Earth” Mean for Us?|Matthew R. Francis|April 18, 2014|DAILY BEAST
An array of whittled bamboo sticks, each four millimeters in diameter, makes up the two-room installation.The Royal Academy Wants You to Finish This Artwork|Chloë Ashby|January 24, 2014|DAILY BEAST
The doctors discovered the entry wound into the frontal lobe with a diameter about equal to that of a cigarette.
Using a 2-inch (5cm) diameter ring cutter, cut the scallops into straight cylinders; reserve the trim.Daniel Boulud Reveals His 4 Favorite Recipes From His New Cookbook|Daniel Boulud|October 15, 2013|DAILY BEAST
Pi is officially defined as the ratio of the circumference of a circle to its diameter.
Today the seven Centennial trees are about two feet in diameter and about 60 feet high.
It is enveloped in a delicate vesicle, the diameter of which is very much greater than that of the contained ovum.The Works of Francis Maitland Balfour, Volume II (of 4)|Francis Maitland Balfour
Many of the pines on this ridge were two feet in diameter, and a hundred feet high, with small clusters of limbs around the tops.
This lake was nearly round, and probably somewhat less than one-half mile in diameter.
All along the side of the road extended an array of huge new pipes, some three feet in diameter, awaiting their turn underground.The Adventures of a Three-Guinea Watch|Talbot Baines Reed
British Dictionary definitions for diameter
- a straight line connecting the centre of a geometric figure, esp a circle or sphere, with two points on the perimeter or surface
- the length of such a line