oxymoron

Noun B2 – Upper-Intermediate

A phrase that combines two contradictory words for effect, such as 'deafening silence'.

"'Jumbo shrimp' is a well-known oxymoron because 'jumbo' and 'shrimp' seem to contradict each other."

The plural can be either 'oxymorons' or the more classical 'oxymora'.