chi-square test

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A test that uses the chi-square statistic to test the fit between a theoretical frequency distribution and a frequency distribution of observed data for which each observation may fall into one of several classes.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun mathematics any statistical hypothesis test in which the test statistic has a chi-square distribution if the null hypothesis is true