an activity done in addition to one's main job, especially to earn extra income
a sideline career as a stand-up comic
either of the two lines bounding the longer sides of a football field, basketball court, tennis court, or similar playing area
Gascoigne celebrated his goal by sprinting to the sidelines
a position where one is observing a situation rather than being directly involved in it
the US has chosen to remain on the sidelines
we are not just watching from the sidelines, we are rolling our sleeves up and getting involved
cause (a player) to be unable to play in a team or game
an ankle injury has sidelined him for two weeks
remove from the centre of activity or attention; place in a less influential position
backbench MPs have been sidelined and excluded from decision-making