a. A line along either of the two sides of a playing court or field, marking its limits.
b. sidelines The space outside such limits, occupied by coaches, inactive players, and spectators.
2. sidelines The position or point of view of those who observe rather than participate in an activity: the political sidelines.
3. A subsidiary line of merchandise.
4. An activity pursued in addition to one's regular occupation.
tr.v. side·lined, side·lin·ing, side·lines
To remove or keep from active participation.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.