antithesis

2. The second part of a sentence or idea that contrasts with the first part.

In 'to err is human, to forgive divine,' the second phrase is the antithesis of the first.

3. A way of writing that puts two opposite ideas close together for effect.

The poem uses antithesis, setting light against darkness in every line.

4. Something that is the complete opposite of another thing in character.

His calm manner was the antithesis of her fiery temper.