1. The correspondence of the form and arrangement of elements or parts on opposite sides of a dividing line or plane or about a center or an axis:the symmetry of a butterfly's wings.
2. A relationship in which there is correspondence or similarity between entities or parts:the symmetry of the play, which opens and ends with a speech by a female character.
3. Beauty as a result of pleasing proportions or harmonious arrangement:"Here were the ringlets, framing a face of exquisite symmetry"(Clive Barker).
4. Physics Invariance under transformation. For example, a system that is invariant under rotation has rotational symmetry.
[Latinsymmetria, fromGreeksummetriā, fromsummetros, of like measure : sun-, syn- + metron, measure; see mē-2 in the Appendix of Indo-European roots.]
(click for a larger image)symmetry
top: bilateral symmetry
bottom: radial symmetry
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 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.