least squares

WordReference Random House Unabridged Dictionary of American English © 2026

least′ squares′, [Statistics.]

1. Statistics 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.

Also called least′-squares′ meth′od, method of least squares. 

• 1860–65

Collins Concise English Dictionary © HarperCollins Publishers::

least squares noun

1. 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