n. & v.
--n.
1. work etc. done in addition to one's main activity.
2 (usu. in pl.) a a line bounding the side of a hockey-pitch, tennis-court, etc. b the space next to these where spectators etc. sit.
--v.tr. US remove (a player) from a team through injury, suspension, etc.
Phrases and idioms:
on (or from) the sidelines in (or from) a position removed from the main action.