WordNet (r) 3.0 (2006):

standard deviation
    n 1: the square root of the variance

Moby Thesaurus II by Grady Ward, 1.0:

31 Moby Thesaurus words for "standard deviation":
   allowance, approximation, deviation, frequency curve,
   frequency distribution, game theory, imprecision, inaccuracy,
   inaccurateness, incorrectness, inexactitude, inexactness, laxity,
   looseness, mathematical probability, negligence,
   operations research, predictability, predictable error,
   probability theory, probable error, quantum mechanics,
   statistical mechanics, statistical probability, statistics,
   tolerance, uncertainty principle, uncorrectness, unfactualness,
   unpreciseness, unrigorousness



The Free On-line Dictionary of Computing (30 December 2018):

standard deviation

    (SD) A measure of the range of values in a set of
   numbers.  Standard deviation is a statistic used as a measure
   of the dispersion or variation in a distribution, equal to the
   square root of the arithmetic mean of the squares of the
   deviations from the arithmetic mean.

   The standard deviation of a random variable or list of numbers
   (the lowercase greek sigma) is the square of the variance.
   The standard deviation of the list x1, x2, x3...xn is given by
   the formula:

    sigma = sqrt(((x1-(avg(x)))^2 + (x1-(avg(x)))^2 +
                 ...  + (xn(avg(x)))^2)/n)

   The formula is used when all of the values in the population
   are known.  If the values x1...xn are a random sample chosen
   from the population, then the sample Standard Deviation is
   calculated with same formula, except that (n-1) is used as the
   denominator.

   [dictionary.com (http://dictionary.com/)].

   ["Barrons Dictionary of Mathematical Terms, second edition"].

   (2003-05-06)