Smart means having or showing intelligence, good judgment, or quick thinking. A smart student might grasp new concepts quickly in math class or figure out creative solutions to tricky problems. Someone who makes a smart decision thinks carefully about the consequences before acting.

The word often describes different kinds of intelligence. You might be book smart (good at learning from reading and studying) or street smart (good at understanding people and navigating real-world situations). A smart move in chess shows you're thinking several steps ahead. A smart answer in class demonstrates you understand the material deeply, not just superficially.

Smart can also mean neat, stylish, or clean in appearance, like wearing your smartest clothes to a wedding. This usage is more common in British English.

When something stings sharply, like when you scrape your knee, it smarts. You might say “that smarts!” when you bump your elbow on a table corner.

People sometimes use smart sarcastically. If someone says “real smart” after you spill milk everywhere, they mean the opposite. A smart aleck (or smarty-pants) is someone who shows off their knowledge in an annoying way or makes clever remarks that aren't really helpful.

Being smart means using your mind well, whether that means solving problems, understanding situations, or making wise choices. It involves applying knowledge and thinking effectively, not just memorizing information.