criterion

1605–15; < Greek kritḗrion a standard, equivalent to kri- variant stem of krī́nein to separate, decide + -tērion neuter suffix of means (akin to Latin -tōrium -tory²)

measure, touchstone, yardstick. See standard.

Like some other nouns borrowed from the Greek, criterion has both a Greek plural, criteria, and a plural formed on the English pattern, criterions. The plural in -a occurs with far greater frequency than does the -s plural: These are the criteria for the selection of candidates. Although criteria is sometimes used as a singular, most often in speech and only infrequently in edited prose, in standard English, it is more clearly used as a plural with criterion as the singular.