1. In logic, the inference that if a conditional statement is true, then its contrapositive is also true. The contrapositive of 'if P then Q' is 'if not Q then not P'.
The contraposition of 'if it rains, the ground is wet' is 'if the ground is not wet, it did not rain'.
A contraposição de 'se chover, o chão fica molhado' é 'se o chão não está molhado, não choveu'.
2. The act or process of placing two things in contrasting positions or juxtaposition.
The contraposition of the old building against the modern skyscraper created a striking visual effect.
A contraposição do edifício antigo contra o arranha-céu moderno criou um efeito visual impressionante.