Criterion / Criteria
Different formsCriterion is singular; criteria is plural. Pair “one” or “a” with criterion, and use a plural verb with criteria.
Criterion
Use when
You mean one standard used to judge or decide something.
Example
“Cost is one criterion in the assessment.”
Criteria
Use when
You mean two or more standards used to judge or decide something.
Example
“The assessment criteria include cost, feasibility and impact.”
Quick check
one criteria, a criteria, the criteria is
Usage note