a method of estimating values from a set of observations by minimizing the sum of the squares of the differences between the observations and the values to be found.

Origin of least squares

First recorded in 1860–65

Also called least-squares method,method of least squares.

British Dictionary definitions for least-squares method

least squares

noun

a method for determining the best value of an unknown quantity relating one or more sets of observations or measurements, esp to find a curve that best fits a set of data. It states that the sum of the squares of the deviations of the experimentally determined value from its optimum value should be a minimum