1
- an activity done in addition to one's main job, especially to earn extra income（尤指挣取外快的）副业, 兼职：
as modifier a sideline career as a stand-up comic.一份做单人说笑喜剧演员的兼职工作。
1.1
- an auxiliary line of goods or trade兼售的货类; 附带的贸易：
electronic handbooks are a lucrative sideline for the firm.
电子手册是这家公司赚钱的附带商品。
2
- （一般作sidelines）either of the two lines bounding the longer sides of a football field, basketball court, or similar（足球场、篮球场等的）边线。
2.1
- the area immediately outside such lines as a place for non-players, substitutes, or spectators（供非运动员、替补队员或观众坐的）场外区域。
with obj.(常作be sidelined)
1- cause (a player) to be unable to play in a team or game使（运动员）无法参赛：
an ankle injury has sidelined him for two weeks.
踝部受伤已迫使他停赛两周。
1.1
- figurative remove from the centre of activity or attention; place in a less influential position〈喻〉使靠边; 使降格：
back-bench MPs have been sidelined and excluded from decision-making.
后座议员已经靠边站, 无权参与决策。
短语
on（或from）the sidelines
- in (or from) a position where one is observing a situation but is unable or unwilling to be directly involved in it当旁观者, 当局外人。