n.[C]

1. 旁线；横线；侧道
2. 副职，兼职；副业
   Joe is an engineer, but he does some translation as a sideline.

   乔是工程师，但作为副业他也从事一些翻译。

3. （球场等的）界线；界线外（观众观看）的场地[P1]
   They watched the match from the sidelines.

   他们站在界线外看比赛。

4. 局外人的观点[P1]

v.

1. 使退出比赛；使下场
   The football player has been sidelined by a foot injury.

   那名足球运动员因脚部受伤而退出比赛。

2. 使靠边；使边缘化

n.

1. an activity done in addition to one's main job.
2. either of the two lines bounding the longer sides of a football field, basketball court, or similar.
3. (the sidelines) a position of observing a situation rather than being directly involved in it.

v.