sideline: Meaning and Definition of

side•line

1. a line at the side of something.
2. a business or activity pursued in addition to one's primary business; a second occupation.
3. an additional or auxiliary line of goods: a grocery store with a sideline of household furnishings.
1. either of the two lines defining the side boundaries of a field or court.
2. sidelines,the area immediately beyond either sideline, where the substitute players sit.

1. to render incapable of participation, esp. in anything involving vigorous, physical action, as a sport: An injury to his throwing arm sidelined the quarterback for two weeks.