midpoint
noun [ C usually singular ] uk/ˈmɪd.pɔɪnt/ us/ˈmɪd.pɔɪnt/
(DISTANCE)
（线等的）中点
a point half the distance along something such as a line
The driveway is 20 metres long, so the midpoint must be at 10 metres. 这条车道有20米长，所以中点一定在10米处。
(TIME)
（时间的）一半，中间时刻
a point in the middle of a period of time
the midpoint of the football season 足球赛季过半的时候