Antagonism may refer to:
The characteristic of an antagonist Antagonism (chemistry), where the involvement of multiple agents reduces their overall effect Drug antagonism, a drug that stops the action or effect of another substance, preventing a biological response Receptor antagonism or pharmacological antagonism, the action of a drug that inhibits the function of an agonist at the level of a receptor Antagonism (phytopathology), an effect that suppresses the activity of a plant pathogen Reflexive antagonism of muscles Intraspecific antagonism, disharmonious or antagonistic interaction between two individuals of the same species
See also Antagonist (disambiguation)