root mean square

American

noun

Mathematics.

the square root of the arithmetic mean of the squares of the numbers in a given set of numbers. rms

root mean square British

noun

rms. the square root of the average of the squares of a set of numbers or quantities

the root mean square of 1, 2, and 4 is √[(1² + 2² + 4²)/3] = √7

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of root mean square

First recorded in 1890–95

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

What is the ratio of the root mean square speeds, urms, of the two gases?

From Textbooks • Feb. 14, 2019

What is the root mean square speed of a N2 molecule at 25 °C?

From Textbooks • Feb. 14, 2019

The root mean square speed of H2 molecules at 25 °C is about 1.6 km/s.

From Textbooks • Feb. 14, 2019

What is the effect on the root mean square speed of the molecules?

From Textbooks • Feb. 14, 2019

Note that the most probable speed, νp, is a little less than 400 m/s, while the root mean square speed, urms, is closer to 500 m/s.

From Textbooks • Feb. 14, 2019

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023