litotes - understatement for rhetorical effect (especially when expressing an affirmative by negating its contrary); "saying `I was not a little upset' when you mean `I was very upset' is an example of litotes"
understatement - a statement that is restrained in ironic contrast to what might have been said
rhetorical device - a use of language that creates a literary effect (but often without regard for literal significance)
Understatement used for effect, especially by negating the opposite, as in not a little angry meaning furious. Also called meiosis. Compare hyperbole.
Etymology: 17c: Greek, meaning ‘small'.
to damn with faint praise, too