The opposite.

(logic) One of a pair of propositions that cannot both be simultaneously true, though they may both be false.

(obsolete) To oppose; to frustrate.

(obsolete) To impugn.

(obsolete) To contradict (someone or something).

(obsolete) To do the opposite of (someone or something).

(obsolete) To act inconsistently or perversely; to act in opposition to.

(obsolete) To argue; to debate; to uphold an opposite opinion.

(obsolete) To be self-contradictory; to become reversed.

Opposite; in an opposite direction; in opposition; adverse.

Opposed; contradictory; inconsistent.

Given to opposition; perverse; wayward.

Contrarily