the enclosing boundary of a curved geometric figure, especially a circle 周线(尤指圆周线) ■the distance around something 周围 babies who have small head circumferences. 头围很小的婴儿们。 [mass noun]two inches in circumference. 周长二英寸。 ■the edge or region which entirely surrounds something 周边;周边地带 petals on the circumference are larger than those in the centre. 位于周边的花瓣要比中间的大些。