No is how you refuse, reject, or deny something. When someone offers you a cookie and you say “no,” you're declining it. When a teacher asks if you've finished your homework and you haven't, the honest answer is “no.”

The word seems simple, but knowing when and how to say no is a useful skill. Sometimes saying no protects you, like when someone pressures you to do something dangerous or wrong. Sometimes it helps you stay focused: if you say no to an extra hour of video games, you might say yes to finishing a project you care about. Sometimes it's just about being honest: answering no when you don't know something is more truthful than pretending you do.

A firm no can be harder to say than you might think, especially to friends or when you worry about disappointing someone. People who never say no can end up overwhelmed, unable to do anything well because they've agreed to do everything.

The word can also mean “not any” or “not one,” as in no time to waste or no students left in the classroom.