Criteria or Criterion: Which Is Correct?

Criterion is singular, criteria is plural — and there is no such thing as “criterias.” One criterion, two or more criteria. Both Collins and Merriam-Webster are unambiguous: Collins’s usage note states “Criteria, the plural of criterion, is not acceptable as a singular noun,” and Merriam-Webster’s usage note warns that phrases like “this criteria” and “single criteria” are widely viewed as erroneous, while the plural “criterias” is viewed as a mistake and usually edited out of published prose. The word came into English from Greek kritērion in the seventeenth century, and its Greek plural has survived intact for four hundred years.

What “criterion” means

A criterion is a standard, rule, or test on which a judgment or decision can be based — Merriam-Webster’s definition — or, as Collins puts it, “a standard by which something can be judged or decided.” Philosophy gives it a second, narrower sense: a defining characteristic of something. In ordinary writing you will meet it wherever selection, evaluation, or eligibility is discussed: hiring criteria, admission criteria, the criteria for a refund, diagnostic criteria in medicine.

The word travels with a family of verbs — meet, satisfy, fulfil, apply — and with the construction criterion for: “the criteria for measuring how good schools are,” “academic ability is not the sole criterion for admission.” These collocations are worth noticing because they are the sentences where the singular/plural question actually bites. “The criteria for admission is…” fails at the verb before the reader even reaches the end of the clause.

Merriam-Webster dates the word’s English life precisely: criterion entered English between 1605 and 1615, taken from Greek kritērion, “a standard,” formed from kri-, a variant of krīnein, “to separate, decide,” plus the neuter suffix -terion (akin to Latin -torium). Collins gives the same Greek chain one step shorter: from kritēs, “judge,” from krinein, “to decide.” Either way, the word arrived carrying its Greek grammar with it — and that grammar is exactly what modern writers keep tripping over.

The Greek plural that English kept

Most English plurals are boring: add -s and move on. But words borrowed directly from Greek (and Latin) sometimes keep their original plural endings, and criterion is one of the survivors. In Greek, neuter nouns ending in -on form their plural in -a: hence criterion → criteria, exactly parallel to phenomenon → phenomena and bacterium → bacteria. The -a ending is a neuter plural ending in both Greek and Latin, and English simply adopted the pair wholesale in the seventeenth century.

Dictionaries also record a fully regularized English plural, criterions — Collins lists the plural as “-ria or -rions,” and American Heritage gives “criteria or criterions.” Criterions is legitimate but rare; Merriam-Webster notes that the plural in -a occurs with far greater frequency than the -s plural. In practice, nobody writes criterions in edited prose, and introducing it will look eccentric. Use criteria.

What makes this pair harder than phenomenon/phenomena is frequency. Because decisions so often rest on more than one factor, the plural criteria shows up far more often in English than the singular criterion — Merriam-Webster’s own usage article makes this observation. When a word’s plural form is the one you see ninety percent of the time, your brain starts treating the plural as the base form, and the singular starts to feel like a fussy invention. It is not. The singular is the original; the plural is just the more popular sibling.

Agreement: the verb always knows

If you are ever unsure which form you have written, let the verb decide — subject-verb agreement forces the question into the open:

Form	Number	Correct pairing	Example
criterion	Singular	is, was, this, a, one	This criterion is not valid.
criteria	Plural	are, were, these, many, several	These criteria are not valid.

Collins’s usage note gives exactly this pair as its model sentences: “this criterion is not valid; these criteria are not valid.” Memorize them. If your sentence reads “the main criteria is,” the is has just told you that your subject is wrong — or your verb is. One of them has to change.

Correct and incorrect, in sentences

• ✓ The primary criterion for selection was experience. — one standard, singular noun, singular verb.
• ✓ All of the criteria must be met for your application to be considered. — multiple standards, plural verb.
• ✓ Academic ability is not the sole criterion for admission to the college. — Collins’s own example; note sole criterion, not “sole criteria.”
• ✓ To qualify for a grant, students must satisfy certain criteria. — the standard verb satisfy with the plural.
• ✗ The main criteria is cost. — the classic error: singular verb with a plural noun. Write The main criterion is cost or The main criteria are cost and speed.
• ✗ We only need one criteria to make a decision. — one demands the singular: one criterion.
• ✗ The selection criterias were unclear. — criterias does not exist; the plural of criterion is already criteria. Adding an -s is doubling the plural, like “childrens.”
• ✗ This criteria was decided by the committee. — this is singular; write This criterion was decided or These criteria were decided.

Common mistakes

“The criteria is.” The single most common error in business and academic writing. It survives because criteria ends in -a, which does not look plural to English-trained eyes the way -s does. But it is plural — Greek plural, four hundred years standing — and Merriam-Webster calls “this criteria” and “single criteria” widely viewed as erroneous. Fix the verb or fix the noun; never leave them disagreeing.

“A criteria” / “one criteria.” The determiner test is instant: a and one are singular, so they can only introduce criterion. “A criteria” is as wrong as “a geese.” If you catch yourself writing it, you meant a criterion.

“Criterias.” Doubly wrong: the plural is already formed (in Greek, with -a), so adding English -s stacks two plural markers. American Heritage’s usage note says it plainly: the plural criterias “is also viewed as a mistake and is usually edited out of published prose.” Editors delete it on sight.

Assuming the dictionaries will eventually surrender. It is true that “criteria” as a singular is heard in speech — Merriam-Webster acknowledges it occurs “sometimes… most often in speech and rather infrequently in edited prose.” But its own conclusion is that criteria “continues strongly in use as a plural in standard English, with criterion as the singular,” and no major dictionary or style guide endorses the singular use. In edited writing, the rule stands.

A compact memory rule: criterion ends in -on like phenomenon, and criteria ends in -a like phenomena. If you can get phenomena right, you already know how to get criteria right — the two pairs rhyme in grammar as well as in sound.

FAQs

Is “criteria” singular or plural?

Plural — always, in standard English. Criteria is the plural of criterion. Collins’s usage note is explicit: “Criteria, the plural of criterion, is not acceptable as a singular noun.” If you mean one standard, write criterion.

Can I say “this criteria”?

No. This is singular and criteria is plural, so the pairing breaks agreement. Merriam-Webster’s usage note lists “this criteria” and “single criteria” as widely viewed as erroneous. Write this criterion or these criteria.

Is “criterias” a word?

No. The plural of criterion is criteria (or, very rarely, criterions) — there is no form criterias. Adding -s to an already-plural Greek ending is an error that editors routinely remove from published prose.

What’s the difference between “criteria” and “criterions”?

Both are recorded plurals of criterion, but criteria is overwhelmingly the standard form; criterions — the regularized English -s plural — is legitimate yet rare enough to look unusual in edited writing. Use criteria.

How do you pronounce “criterion” and “criteria”?

Criterion is /kraɪˈtɪərɪən/ in British English (kry-TEER-ee-uhn) and /kraɪˈtɪriən/ in American English; criteria is /kraɪˈtɪərɪə/ (kry-TEER-ee-uh) in both. The stress sits on the second syllable in each.

Why is the plural so irregular?

Because English borrowed the whole Greek word-pair intact in the 1600s: Greek neuter nouns in -on take -a in the plural. The same borrowing gives us phenomenon/phenomena. Four centuries of use have not worn the Greek ending away, so the irregular plural survives.

Takeaway

One criterion, two criteria, zero criterias. The singular takes is, this, and a; the plural takes are, these, and many. Borrowed from Greek kritērion in the early 1600s and defined by every major dictionary as a standard for judgment, the word has kept its Greek plural for four hundred years — and both Collins and Merriam-Webster agree that treating criteria as singular is an error, not an evolution. Let the verb be your enforcer: if it says is, the noun must be criterion.