Plural of “criterion”

The plural of criterion is criteria.

Why

"Criterion" comes directly from Greek "kriterion," meaning "a means of judging." Unlike "cactus" or "octopus," it kept its Greek plural pattern intact and largely unchallenged: Greek neuter nouns ending in -on typically pluralize with -a, which is exactly the pattern also seen in "phenomenon/phenomena" and "automaton/automata."

Because "criterion" is used almost exclusively in careful, formal, or academic writing (evaluation standards, research methodology, grading rubrics), it hasn't drifted toward a regularized "criterions" plural the way more everyday Latin/Greek borrowings like "cactus" have — its narrow, formal usage context has kept the original Greek plural firmly in place. Unlike "phenomenon," "criterion" has essentially never developed a colloquial or figurative sense that might tempt writers toward a regularized plural — it remains a purely technical, evaluative term across every register it appears in, from academic grading to job-interview scorecards, which likely explains why "criterions" is virtually nonexistent even in the most casual writing, unlike the occasional "phenomenons" seen for remarkable people.

Usage note

The most important usage note isn't about spelling at all but about number agreement: "criteria" is plural and takes a plural verb ("the criteria are clear"), while the singular "criterion" takes a singular verb ("the criterion is clear") — using "criteria" as if it were singular ("this criteria is important") is one of the most common errors among fluent English speakers with this particular word. In everyday spoken English, many fluent speakers now use "criteria" as a de facto singular without much pushback in casual conversation, even though careful editing still treats it as an error — a live example of a classical plural potentially reanalyzing as a new singular over time, the same fate that eventually overtook the Latin word "agenda" (originally a plural, now treated as singular in modern English).

The criterion/criteria distinction is one of the most reliably tested points in formal writing and editing courses precisely because the error is so easy to make and so noticeable to a careful reader once you know to look for it — a single misused "criteria" in an otherwise polished piece of writing is often enough to make a reader question the writer's overall command of formal register. Software and search-interface writing has added a further wrinkle: "search criteria" is now extremely common as a fixed technical phrase, and interface copywriters sometimes use it as if it were a mass, uncountable noun ("enter your criteria") rather than a true countable plural, blurring a distinction that formal style guides like the AP Stylebook and Chicago Manual of Style still insist on maintaining strictly in edited prose.

Common real mistakes

Treating "criteria" as a singular noun ("one criteria," "this criteria") is by far the most frequent mistake; if you mean just one, the correct singular is always "criterion." Because "criteria" so often appears in bulleted lists in business and technical documents, writers also sometimes pair a plural "criteria" with a singular verb purely by proximity to a nearby singular noun in the sentence ("the criteria for success is clear"), a subject-verb agreement slip distinct from, but closely related to, treating "criteria" as singular outright.

The wider pattern

This is the same Greek neuter -on/-a pattern behind "phenomenon/phenomena" and the much rarer "automaton/automata" — all three entered English through formal academic, scientific, or philosophical writing and have kept their Greek plurals largely intact because their usage has stayed concentrated in registers where speakers are more likely to have absorbed the classical pattern rather than defaulting to regular English pluralization.

Examples

• The judges outlined three criteria for scoring the competition.
• One criterion stood out as more important than the rest.
• These criteria are used to evaluate every application equally.
• The main criterion for admission is a strong portfolio.
• Reviewers apply the same criteria to every submission.
• Meeting a single criterion isn't enough to qualify.
• Each criterion was weighted differently in the final score.
• The committee agreed on five criteria before reviewing applications.
• Without clear criteria, the judging felt inconsistent.
• The strictest criterion eliminated half the candidates immediately.