An oxymoron is defined by Willard Espy in the Garden of Eloquence (Harper and Row, 1983) as "a figure in which an epithet of contrary meaning is added to a word". He gives several examples, including "their love was bittersweet, "wise folly, and "a deafening silence".
"The Great Oxymoron Contest,"
Word Ways: Vol. 16
, Article 3.
Available at: http://digitalcommons.butler.edu/wordways/vol16/iss4/3