an activity that you do as well as your main job in order to earn extra money

the lines along the two long sides of a sports field, tennis court, etc. that mark the outer edges; the area just outside these

<i>The coach stood on the sidelines yelling instructions to the players.</i>

to prevent somebody from playing in a team, especially because of an injury

to prevent somebody from having an important part in something that other people are doing

<i>The vice-president is increasingly being sidelined.</i>

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