noun
litotes; meiosis
A rhetorical device where an affirmative is expressed by negating its opposite, often for understatement or ironic effect. Technical term used in literary analysis.
「悪くない」という表現は緩叙法の一例だ。
The expression 'not bad' is an example of litotes.
彼のスピーチには緩叙法が多用されていた。
His speech made frequent use of litotes.
修辞法 is a general term for rhetorical devices; 緩叙法 is a specific type.
From 緩 (gentle, moderate) + 叙 (describe, relate) + 法 (method, rule), a calque of the Western rhetorical term 'litotes'.