The use of words in a sense opposite to their proper meaning; as when a court of justice is called a court of vengeance.

Use of an expression where its exact opposite would be appropriate. Antiphrasis usually is intended to produce an ironic or humorous effect. Examples: a bald man called "Curly" or a tall fat man called "Tiny"

the use of a word in a sense opposite to its normal sense (especially in irony)

12.97.12 up Ironic use of a word for its opposite

An antiphrasis (from Greek and Latin: anti, opposite, and phrasis, diction) is a figure of speech that is a word used in an abnormal sense especially ironic.