Definition of "symmetric" [sym•met•ric]

• Symmetrical. (adjective)
• Of a relation R on a set S, such that xRy if and only if yRx for all members x and y of S (that is, if the relation holds between any element and a second, it also holds between the second and the first). (adjective)
• Using the same key (or keys that are trivially related) for both encryption and decryption. (adjective)

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• "It's the belief in symmetric fluctuations that drives the focus on policy rules rather than policy events."
• "It shows how we human beings see the objects around us in symmetric shapes."
• "This phenomenon, of nature being non-mirror symmetric, is known as CP violation, and rocked the physics world when it was discovered experimentally in the 60’s."