I came across several forums and articles saying that criteria is plural and criterion is singular. Some gave me the impression that criterion is used to denote a set of rules.

What is the correct use of these two words?

  • So is it correct to say "There are three criteria to this project?"
    – user18795
    Commented Mar 5, 2012 at 20:39
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    @Mike: 'one criterion', 'three criteria'. 'criteria/on to this..' sounds weird. Use 'criteria for...'. Though your punctuation is probably correct for American writing, from a logical use/mention aspect, you should say: '... "...this project." ?'. That is, the punctuation for the quote, inside the quote and the punctuation for the sentence at large outside the quote.
    – Mitch
    Commented Mar 5, 2012 at 22:48

5 Answers 5


According to Merriam-Webster.com, criteria is indeed plural and criterion is singular. The dictionary definition is "a standard on which a judgement or decision may be made"; it's often used synonymously with "requirement(s)", as in "if you don't meet the criteria you won't be allowed in" or "I have one all-important criterion by which I judge potential plumbing contractors: is their shirt tucked in to their belted pants?"

M-W.com also notes that the use of "criteria" as singular has been gaining ground for a long time (50 years or so) and may be considered acceptable usage by now.

(To which I say, fight the change! Use "criterion" correctly!)

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    For those for whom criteria is singular, what is the plural? Criterias? Criteriae? Criterions? :-) Commented Feb 12, 2011 at 15:47
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    It's all just "criteria". One criteria, two criteria. Just like fish, I guess.
    – Hellion
    Commented Feb 12, 2011 at 15:49
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    Like fish? I thought the plural of fish was fishies. You know, "Oh, lots of colorful fishies!". Commented Feb 12, 2011 at 17:41
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    +1: I will note that of the three answers here so far, Hellion's is the only one that actually answers the OP's question.
    – Robusto
    Commented Feb 12, 2011 at 17:51
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    @Acco No, "a set of criteria" would be correct, because a set, in standard usage, implies more than one member. (Mathematically, of course, you can have an empty set or a single-member set; but in normal English, a set is taken to be 2 or more items taken together.)
    – Hellion
    Commented Feb 11, 2016 at 6:05

Criterion comes from Classical Greek. Its gender is neuter and it belongs to the second declension — like the word phenomenon.

  • +1 for mentioning phenomenon/a before I had the chance to :-) Commented Feb 12, 2011 at 17:12

I would say that criteria is used to denote a set of rules, and that one of those rules would be a criterion.

Actually, I wouldn't say that, as a criterion and a rule aren't quite the same thing. I'd make a GRE-style analogy: Criteria is to set of rules as criterion is to rule.


You should not use criteria when you mean criterion for the same reason that you should not use criterion when you mean criteria. These is my only criterions. -George Carlin


In English, a lot of nouns have kept the original ending coming from classical Greek or Latin. Criterion is just one of them. In science you find a lot of words with these queer plural forms, but in fact they follow the Greek and latin declensions: Latin: alga- algae stimulus -stimuli bacterium -bacteria species-speciei (except that this one is no longer used, it has been replaced by species, due to the fact that in several modern languages "s" means plural. Greek: a thesis -2 theses an analysis -two analyses a criterion -two criteria

This means that if you know the singular form in "a" or "us" or "um", you can deduce the plural !!

  • 2
    No, there is no general rule for producing a plural given a word that ends in this or that: you can only deduce the original plural if you actually know Latin or Greek. For example, the nominative plural of species in Latin was the very same word, species; the genitive singular was the speciei spelling you erroneously gave. Similarly, you can only know the Latin plural of an -us word if you know its declension, or else you will get their Latin plurals wrong in pairs like genus/genera, corpus/corpora, apparatus/apparatus. You might also get stigma/stigmata wrong from Greek.
    – tchrist
    Commented Dec 3, 2014 at 15:20

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