口径

(1)the length of a straight line passing through the center of a circle and connecting two points on the circumference

(2)円の中心点を通り、円周上の2点をつなぐ直線の長さ

(3)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)

(4)円の中心と円周上の2点（または球の中心と球面上の2点）を結んでいる直線

(5)diameter of a tube or gun barrel

(6)管や銃身の直径

(7)an man-made opening; usually small

(8)人工物の穴

(9)通常小さい

(10)a natural opening in something

(11)開口部