Conviction means a strong, firm belief in something. When you have conviction about an idea or principle, you believe in it deeply and aren't easily swayed by others. Someone with conviction about honesty will tell the truth even when lying would be easier. A scientist with conviction about her theory will keep researching even when others doubt her work.

The word suggests beliefs that carry weight and determination, beliefs you're willing to act on and defend. You might think chocolate ice cream tastes best, but you have conviction that treating people fairly matters. People with conviction often inspire others because their certainty and commitment shine through in their words and actions.

The word also has a legal meaning: in court, a conviction is a formal declaration that someone is guilty of a crime. After a trial, if the jury finds the defendant guilty, that guilty verdict is called a conviction. This legal meaning shares something with the first: just as a personal conviction is a firm belief, a legal conviction is a firm judgment.

Notice how conviction relates to convince: when you're convinced of something, you develop a conviction about it. And people with strong convictions often work to convince others to share their beliefs.