A cheater is someone who acts dishonestly to gain unfair advantages, whether in games, tests, sports, or other activities where rules or trust matter. The word carries weight: calling someone a cheater is a serious accusation because it questions their integrity.

In school, a cheater might copy answers during a test or plagiarize someone else's writing. In sports, a cheater breaks the rules hoping referees won't notice. In card games, a cheater might mark cards or hide aces up their sleeve. Sometimes people use cheater to describe someone who cheats repeatedly or makes it part of how they usually behave.

The label sticks because trust, once broken, is hard to rebuild. If classmates discover someone has been cheating at games during recess, they may stop wanting to play with them. If a scientist cheats by faking research data, other scientists won't trust their future work.

Sometimes people use the word more loosely, like saying “you cheater!” when a friend finds a clever but legal strategy in a video game. That's usually playful teasing, not a real accusation. But when used seriously, cheater identifies someone who has damaged their reputation by choosing dishonesty over playing fair.