Sarcasm is a form of expression THAT uses IRONY to mock or criticize someone or something. It is often used in a humorous way, but can also be used to express contempt or disapproval. The term 'sarcastic use of words' refers to the use of IRONY to make a point or to express an opinion. IRONY is a figure of speech in which words are used to convey the opposite of their literal meaning. For example, if someone says 'THAT's great!' sarcastically, they are actually expressing disapproval or disbelief.