The media seem to have been plagued with expressions like “the criteria is” lately. Unfortunately, such expressions are incorrect, because “criteria” is a plural noun; using it as a singular noun is essentially the same as saying “a houses is”.
If “criteria” is the plural, what’s the singular? The word is based on the Greek pattern -on → -a, so the singular form is criterion. For example:
One could argue that since what is considered correct is decided by usage, saying “a criteria” should be acceptable (as it has become somewhat widespread). However, no major dictionary or manual of style endorses such usage, and most educated native speakers find it wrong, so there is no good reason to use “criteria” as a singular noun.