[sahyd-lahyn] 
noun, verb, -lined, -lin⋅ing.| 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. |
| 4. | Sports.
|
| 5. | sidelines, the position or point of view taken by a person who observes an activity or situation but does not directly participate in it. |
| 6. | 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. |
