# rotation axis

### noun Crystallography.

an imaginary line through a crystal about which the crystal may be rotated a specified number of degrees and be brought back to its original position.

Compare symmetry element.

## Origin of rotation axis

First recorded in 1900–05

Also called axis of symmetry, symmetry axis of rotation.

## rotation of axes

[ak-seez]

### noun Mathematics.

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Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019