criterion

UK: /kraɪˈtɪərɪən/ US: /kraɪˈtɪriən/ ,(krī tēr′ē ən)

Inflections of 'criterion' (n):

criteria

npl

criterions

npl

WordReference Random House Learner's Dictionary of American English © 2025

cri•te•ri•on /kraɪˈtɪriən/   n. [countable] , pl. -te•ri•a /-ˈtɪriə/  -te•ri•ons. 

1. Pronouns a standard by which to judge or criticize:
   Which criterion is the most important when you grade essays?

WordReference Random House Unabridged Dictionary of American English © 2025

cri•te•ri•on  (krī tēr′ē ən), n., pl. -te•ri•a (-tēr′ē ə), -te•ri•ons. 

1. Pronouns a standard of judgment or criticism;
   a rule or principle for evaluating or testing something.

• Greek krité̄rion a standard, equivalent. to kri- variant stem of krí̄nein to separate, decide + -tērion neuter suffix of means (akin to Latin -tōrium -tory²)
• 1605–15

cri•te′ri•al, adj. 
Synonyms

measure, touchstone, yardstick. See standard. 

Usage

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 rather infrequently in edited prose, it continues strongly in use as a plural in standard English, with criterion as the singular.

Collins Concise English Dictionary © HarperCollins Publishers::

criterion / kraɪˈtɪərɪən/ noun ( -ria / -rɪə/, -rions)

1. a standard by which something can be judged or decided

Etymology: 17th Century: from Greek kritērion from kritēs judge, from krinein to decideUSAGE
Criteria, the plural of criterion, is not acceptable as a singular noun: this criterion is not valid; these criteria are not valid