standard deviation

noun

1

: a measure of the dispersion of a frequency distribution that is the square root of the arithmetic mean of the squares of the deviation of each of the class frequencies from the arithmetic mean of the frequency distribution

also : a similar quantity found by dividing by one less than the number of squares in the sum of squares instead of taking the arithmetic mean

2

: a parameter that indicates the way in which a probability function or a probability density function is centered around its mean and that is equal to the square root of the moment in which the deviation from the mean is squared

Examples of standard deviation in a Sentence

Recent Examples on the Web

The stock is within one standard deviation of its 80-day moving average. —Schaeffer's Investment Research, Forbes.com, 10 July 2025

One way to look at this is the standard deviation of daily returns—i.e., the amount prices move away from the mean. —Cody Slach, Forbes.com, 23 June 2025

Further emphasizing the impact on economically disadvantaged students, the study noted that the lowest-achieving students benefited the most, with their test scores increasing by 14.23% of a standard deviation. —Kyle Smitley, Forbes.com, 13 June 2025

DataTrek Research co-founder Nicholas Colas noted that international stocks are outpacing the S & P 500 by more than three standard deviations over the past 100 days. —Fred Imbert, CNBC, 28 May 2025

Word History

First Known Use

1895, in the meaning defined at sense 1

Rhymes for standard deviation

• abbreviation
• abomination
• acceleration
• accentuation
• accommodation
• accreditation
• acculturation
• accumulation
• acetylation
• adjudication
• administration
• adulteration

Kids Definition

standard deviation

noun

: the square root of the arithmetic mean of the squares of differences between the arithmetic mean of a frequency distribution and the values of the variable