A criterion is a standard or rule you use to make a decision or judgment about something. When your teacher grades essays, she might use criteria like clear organization, strong evidence, and proper grammar. When you're choosing which book to read next, your criteria might include an exciting plot, interesting characters, and a length that fits your schedule.

Think of criteria as the specific things you're looking for when evaluating options. A basketball coach selecting players for the team might use criteria like shooting accuracy, teamwork, and hustle. A scientist testing a new medicine uses strict criteria to determine whether it actually works.

The singular form is criterion (one standard), while the plural is criteria (multiple standards). You might hear someone say, “The main criterion for this award is academic excellence,” or “We used three criteria to pick our science fair project: originality, feasibility, and cost.”

Criteria help make decisions more fair and consistent. Instead of choosing randomly or based on feelings alone, you can point to specific standards everyone agrees on. When you understand the criteria for something, whether it's making the honor roll or winning a contest, you know exactly what you need to do to succeed.