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.
One who resists, especially a person who fights against an occupying army.
An electric component that transmits current in direct proportion to the voltage across it.