1. To deceive, to defraud, to swindle, or to attempt to take something in an illegal manner: One of the first lessons the students learned was that to cheat on their homework or on their tests would result in failing grades.

Bert's neighbor tried to cheat on his taxes, subs decided not to after all.

2. To take advantage of others by lying or breaking a rule: The store tried to cheat its customers with false advertising.