A figure of speech in which something is described by means of what it is not, a rhetorical device expressing ideas through negation or contradiction.
From Greek 'dia-' (through) + 'syrm' (possibly related to 'syrrhapto', meaning to tear or rend), though the exact etymology is obscure. The term appears in classical rhetoric to describe a specific manner of expression through denial or opposition.
Paradoxically, saying what something isn't can sometimes be clearer than saying what it is—this is why 'not bad' can mean quite good, and why negative space in art makes shapes appear more defined.
Complete word intelligence in one call. Free tier — 50 lookups/day.