If a person is sarcastic, they use words to mean the opposite of what the dictionary says. It is normally done as a form of humour, but it can sometimes be an unpleasant form of humour as it can be used to laugh at people. For example, if someone didn't enjoy the a meal, they could say how much they enjoyed it in an exaggerated way, knowing that people would understand that they meant the opposite, which would hurt the cook. It doesn't have to be unpleasant- among friends it's a common way of joking.
- For Teachers