diameter
noun [ C or U ] uk/daɪˈæm.ɪ.tər/ us/daɪˈæm.ə.t̬ɚ/
直径
(the length of) a straight line that reaches from one point on the edge of a round shape or object, through its centre, to a point on the opposite edge
The diameter measures twice the radius. 直径是半径的两倍。
The pond is six feet in diameter. 这个池塘的直径为6英尺。