sideline

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Sports A line along either of the two sides of a playing court or field, marking its limits.
2. n. Sports The space outside such limits, occupied by coaches, inactive players, and spectators.
3. n. The position or point of view of those who observe rather than participate in an activity: the political sidelines.
4. n. A subsidiary line of merchandise.
5. n. An activity pursued in addition to one's regular occupation.
6. v. Informal To remove or keep from active participation.

Century Dictionary and Cyclopedia

1. n. A line pertaining or attached to the side of something; specifically, in the plural, lines by which the fore and hind feet on the same side of a horse or other animal are tied to prevent straying or escape.
2. n. A line or course of business aside from or additional to one's regular occupation.
3. To hobble, as a horse.
4. n. In foot-ball, hockey, and similar games, a line defining the limit of play on the side of the field, and outside of which the ball is out of bounds.

Wiktionary

1. n. A line at the side of something, as in "the yellow sideline of the road".
2. n. sports A line defining the side boundary of a playing field.
3. n. usually plural The area outside the playing field beyond each sideline.
4. n. The outside or perimeter of any activity.
5. n. Something that is additional or extra or that exists around the edges or margins of a main item.
6. v. transitive To place on the sidelines; to bench or to keep someone out of play.
7. v. transitive To remove or keep out of circulation.

GNU Webster's 1913

1. A line pertaining or attached to the side of a thing.
2. Specif., a line for hobbling an animal by connecting the fore and the hind feet of the same side.
3. Canada, Canada A line of goods sold in addition to one's principal articles of trade; a course of business pursued aside from one's regular occupation.
4. Canada A secondary road; esp., a byroad at right angles to a main road.

WordNet 3.0

1. n. an auxiliary line of merchandise
2. v. remove from the center of activity or attention; place into an inferior position
3. n. an auxiliary activity
4. n. a line that marks the side boundary of a playing field