n.

1. 【数】周
2. 周围；边缘
3. 【军】周边阵地
4. 【物】视野计

n.

1. the continuous line forming the boundary of a closed geometrical figure.
2. the outermost parts or boundary of an area or object.
3. Basketball  an area away from the basket, beyond the reach of the defensive team.
4. an instrument for measuring the extent and characteristics of a person's field of vision.