An antiphrasis (pron.: //; from the Greek: ἀντί, antí, "opposite" and φράσις, phrásis, "diction") is a figure of speech in which a word or phrase is used to mean the opposite of its usual sense, especially ironically.
"It was a bold antiphrasis that gave such a vernal title [Greenland] to this birth-place of icebergs."
See also 
- Rollin's Anc. Hist. (1827) VII. XVIII. i. 202.
- KANE Grinnell Exp. iv. (1856) 33. From Oxford English Dictionary