di|am|e|ter

di|am|e|ter «dy AM uh tuhr», noun.

1. a straight line passing from one side to the other through the center of a circle, sphere, cylinder, or other rounded form.

2. the length of such a line; measurement from one side to the other through the center of a figure or object; width; thickness: »

the diameter of a pipe, rock, or crater. The diameter of the earth is about 8,000 miles. The tree trunk was almost 2 feet in diameter.

3. a measure of the degree of magnification of a microscope or telescope lens. A microscope that makes an object appear 10 times larger has magnified the object 10 diameters, usually written 10X. Abbr: d., dia., diam.

╂[< Old French diametre, learned borrowing from Latin diametros < Greek diámetros diagonal of a circle or parallelogram < dia- across + métron a measure]