sideline
US /ˈsaɪd.laɪn/
UK /ˈsaɪd.laɪn/

1.
a line at each side of the playing area of a sports field or court
:
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The coach stood near the sideline, shouting instructions.
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The ball went out of bounds over the sideline.
2.
a position of not being actively involved in something
:
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He was forced to the sideline due to injury.
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Many investors remained on the sidelines during the market downturn.
1.
to remove someone from active participation or involvement in an activity or event
:
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The coach decided to sideline the injured player for the rest of the season.
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The new policy might sideline some of the older employees.