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
least squares in American English
a statistical method used to find the curve that most closely approximates a set of data: it is based on minimizing the sum of the squares of the differences between expected and observed values of the data