square root

American  

noun

1. a quantity of which a given quantity is the square.

   The quantities +6 and −6 are square roots of 36 since (+6)×(+6)=36 and (−6)×(−6)=36.

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square root British  

noun

1. a number or quantity that when multiplied by itself gives a given number or quantity

   2 is a square root of 4, usually written √4 or 41/2

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square root Scientific  

1. A number that, when squared, yields a given number. For example, since 5 × 5 = 25, the square root of 25 (written √25) is 5.

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square root Cultural  

1. A number that, when multiplied by itself, will result in a given number. The square root of four is two; the square root of one hundred is ten.

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Discover More

The square roots of many numbers, such as three, are irrational numbers.

Etymology

Origin of square root

First recorded in 1550–60

Example Sentences

I was smiling because I was remembering the square root of eight.

From Los Angeles Times • Jan. 8, 2026

Why is the square root of -1 called i?

From Salon • Jul. 29, 2024

England gave them the square root of nothing.

From BBC • Sep. 9, 2023

“If you’ve ever tried to compute the square root of 285, then you have an idea of how it feels to deliberate,” explains Ralf Schmälzle, a communication neuroscientist at Michigan State University.

From National Geographic • Aug. 17, 2023

Two was always the square root of four.

From "The Strangers" by Margaret Peterson Haddix