litotes

[ lahy-tuh-teez, lit-uh-, lahy-toh-teez ]
/ ˈlaɪ təˌtiz, ˈlɪt ə-, laɪˈtoʊ tiz /

noun, plural li·to·tes. Rhetoric.

understatement, especially that in which an affirmative is expressed by the negative of its contrary, as in “not bad at all.”
Compare hyperbole.

Origin of litotes

1650–60; < New Latin < Greek lītótēs orig., plainness, simplicity, derivative of lītós plain, small, meager

British Dictionary definitions for litotes

litotes
/ (ˈlaɪtəʊˌtiːz) /

noun plural -tes

understatement for rhetorical effect, esp when achieved by using negation with a term in place of using an antonym of that term, as in "She was not a little upset" for "She was extremely upset."

Word Origin for litotes

C17: from Greek, from litos small