Irony & Understatement
Meiosis / Understatement
Deliberately understating the size or importance of something: calling a serious wound “a scratch.” The gap between the description and the situation can minimize it or draw attention to its severity.
"'Tis but a flesh wound."
Don't confuse it with Litotes. Litotes is understatement achieved specifically through negation ('not unkind'); meiosis just shrinks the label.
Examples
After the flood carried away the bridge, he called it “a slight inconvenience.”
The description deliberately reduces the scale of a serious disruption.
The rest of the family
Irony Hyperbole Litotes Bathos Euphemism Periphrasis Apophasis