1. Having or formed of two sides; two-sided.
2. Affecting or undertaken by two sides equally; binding on both parties: a bilateral agreement; bilateral negotiations.
3. Relating to both the right and the left side of the body or of a body structure: bilateral mastectomy.
4. Having or marked by bilateral symmetry.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 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.