a basis for comparison; a reference point against which other things can be evaluated
"the schools comply with federal standards"
"they set the measure for all subsequent work"
A standard or test by which individual things or people may be compared and judged.
"The committee used safety records as the primary criterion for selecting new drivers."
In plain English: A criterion is a standard used to judge whether something meets certain requirements.
"The teacher used punctuality as her main criterion for grading students."
Usage: Use the singular form criterion when referring to one standard, but switch to its plural counterpart criteria whenever you mention two or more standards. This distinction is essential because many speakers incorrectly use criterions as a plural.
The word criterion comes from the New Latin form of an Ancient Greek term meaning "a test" or "means of judging." It entered English through this intermediate language stage rather than directly from its original source.