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.
political spectrumRead more in this article about some frequently asked questions and fun facts related to our definitions.
When To Capitalize “Earth”When it comes to writing, this common English word confuses many native speakers who aren’t sure whether to use Earth or earth. Why is this an issue? Earth can be either a proper noun or a common noun. In English, proper nouns (nouns which signify a particular person, place, or thing) are capitalized. Following this rule, when Earth is discussed as a specific planet or …
Compare symmetry element.
Origin of rotation axis
First recorded in 1900–05
Also called axis of symmetry, symmetry axis of rotation.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019