1. generally, any action in opposition to, defying, or withstanding something or someone.

2. in psychotherapy and analysis, obstruction, through the client’s words or behavior, of the therapist’s or analyst’s methods of eliciting or interpreting psychic material brought forth in therapy. Psychoanalytic theory classically interprets resistance as a defense and distinguishes three types in particular: conscious resistance, id resistance, and repression resistance.

3. the degree to which an organism can defend itself against disease-causing microorganisms. See immunity.

4. the degree to which disease-causing microorganisms withstand the action of drugs. —resist vb. —resistant adj.