A contradiction in terms
Definition 1 of 1
Pro Tip 1/3Spotting Contradictions
Look for combinations of words that oppose each other's meaning. 
Saying 'deafening silence' is a contradiction in terms, as silence cannot make noise.
Pro Tip 2/3Understanding Irony
Sometimes, 'a contradiction in terms' is used to highlight irony in a situation. 
Calling a bankrupt millionaire 'rich' is a contradiction in terms that implies irony.
Pro Tip 3/3Detect Figurative Use
Recognize it as a literary device that can convey complex ideas in a few words. 
The phrase 'living dead' used in stories is a contradiction in terms.