Cheater (noun)

1. A person who engages in deception or acts dishonestly.
2. Someone who breaks the rules in order to gain an advantage.
3. A person who is unfaithful in a relationship.

Origin:

From the verb "cheat" meaning to deceive or to act dishonestly.

Examples:

1. He was caught cheating on the test and received a failing grade.
2. She was known as a cheater and was not well liked by her peers.
3. The cheater was disqualified from the game for breaking the rules.
4. He was a cheater in love and had multiple affairs.
5. The company was caught using cheater tactics to win the bid.