What term refers to a word or phrase that means the exact opposite of its literal meaning?

The term that refers to a word or phrase that means the exact opposite of its literal meaning is sarcasm. Sarcasm typically involves saying something in a way that suggests the opposite is true, often for humorous or ironic effect. For example, if someone sees a messy room and says, "Wow, this place is spotless," they mean the opposite. This use of language conveys a critical or mocking tone, which is characteristic of sarcasm.

The other options focus on different language concepts that don't specifically relate to expressing the opposite of literal meaning. Hyperbole is an exaggerated statement not meant to be taken literally, antonymy refers to words that have opposite meanings but doesn't imply a phrase's ironic or contrary expression, and an oxymoron is a figure of speech that combines contradictory terms, like "deafening silence," but does not denote the use of irony or sarcasm.