The figure of speech that uses understatement by negating the opposite is called litotes. Saying “not bad” to suggest “good” is a classic example, although tone and context determine how strongly the phrase is meant.
Litotes works by deliberately understating an idea, often through a negative construction. A speaker might say “she is not inexperienced” to imply that she is skilled, or “that was no small achievement” to emphasize its importance. The indirect wording can sound modest, ironic, restrained, humorous, or politely less harsh than a direct statement.
The term comes from the ancient Greek λιτότης, associated with simplicity or plainness. The rhetorical technique is especially visible in Old English poetry and Icelandic sagas, where controlled understatement often conveys courage or emotional restraint. Classical rhetorical traditions also grouped it with related forms of diminution and understatement.
Litotes is sometimes confused with euphemism, but they are not identical. A euphemism replaces an unpleasant expression with a gentler one, while litotes specifically achieves its effect through deliberate understatement, commonly by negating a positive or negative term. “Not bad” can even mean merely average if the speaker’s intonation changes.