To defraud someone means to illegally trick them out of their money or property through lies and deception. When con artists defraud elderly people by pretending to be bank officials on the phone, they're stealing through dishonesty rather than breaking into houses. When someone defrauds a company by submitting fake expense reports, they're using lies to take money that isn't theirs.

Defraud is more specific than simply lying or cheating. It involves deliberate fraud (planned dishonesty) to take something of value that belongs to someone else. A scammer might defraud customers by selling fake concert tickets. A corrupt employee might defraud their employer by creating fake invoices for work that was never done.

The word carries serious weight because defrauding people is a crime. Unlike a child fibbing about finishing their homework, someone who defrauds another person has broken the law and can face serious legal consequences. When you hear that someone was convicted of defrauding investors, it means they were found guilty of using lies and trickery to steal money, often in large amounts over a long period of time.