Here are some examples of how "stringent" can be used:
* "The company has stringent safety regulations." (meaning the safety regulations are very strict and must be followed closely)
* "The professor gave a stringent grading rubric." (meaning the grading criteria were very demanding)
* "The bank has stringent loan requirements." (meaning the requirements to get a loan are difficult to meet)
Essentially, something that is stringent is difficult to meet or achieve due to its high demands.