Meiosis

“Meiosis: [Stress: ‘my-OH-sis’] In rhetoric, a kind of understatement that dismisses or belittles, especially by using terms that make something seem less significant than it really is or ought to be: for example, calling a serious wound a scratch, or a journalist a hack or a scribbler.”

Excerpted from: McArthur, Tom. The Oxford Concise Companion to the English Language. New York: Oxford University Press, 2005.