- diameter, diam - the length of a straight line passing through the center of a circle and connecting two points on the circumference
--1 is a kind of length
--1 has parts: radius, r
--1 has particulars: bore, gauge, caliber, calibre; windage - diameter - a straight line connecting the center of a circle with two points on its perimeter (or the center of a sphere with two points on its surface)
--2 is a kind of straight line