circumference
n. 圆周，周长；周边，外围
复数 circumferences
例句
The earth is almost 25 000 miles in circumference.
地球的周长大约为25 000英里。
《牛津词典》
The earth's circumference is about 25,000 miles.
地球的圆周约为25,000英里。
《新英汉大辞典》
I have to have a whole number of wavelengths to get around the circumference.
我必须有很多波长才能绕这个圆周。
