An opponent or enemy.
A muscle that acts in opposition to another.
A chemical that binds to a receptor but does not produce a physiological response, blocking the action of agonist chemicals.
The main character or force opposing the protagonist in a literary work or drama.
One who antagonizes or stirs.
The action of opposing or of being in conflict.
The difference of quantity or quality between two propositions having the same subject and predicate.
A political party or movement opposed to the party or government in power.
In United States intellectual property law, a proceeding in which an interested party seeks to prevent the registration of a trademark or patent.
The apparent relative position of two celestial bodies when one is at an angle of 180 degrees from the other as seen from the Earth.
An opposite or contrasting position.
A position in which the player on the move must yield with his king allowing his opponent to advance with his own king.