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A rule that uses the shape of the right hand to establish the standard orientation of vector quantities normal to a plane, especially when calculating a vector product or the helicity of particle spin. For example, in the case of spin, the fingers of the right hand should curl in the direction of rotation; the thumb then points in the direction of the spin vector.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.