oxymoron

A rhetorical figure in which incongruous or contradictory terms are combined, as in a deafening silence and a mournful optimist.

In rhetoric, a figure consisting in adding to a word an epithet or qualification apparently contradictory; in general, close connection of two words seemingly opposed to each other (as, cruel kindness; to make haste slowly); an expression made epigrammatic or pointed by seeming self-contradictory.

A figure in which an epithet of a contrary signification is added to a word; e. g., cruel kindness; laborious idleness.

A figure of speech in which two words with opposing meanings are used together intentionally for effect.

A contradiction in terms.

conjoining contradictory terms (as in `deafening silence’)