- adhering to a policy of opportunism; practicing opportunism.
- Pathology.
- (of a microorganism) causing disease only under certain conditions, as when a person's immune system is impaired.
- (of a disease or infection) caused by such an organism: Pneumocystis pneumonia is an opportunistic disease that often strikes victims of AIDS.
- of or characterized by opportunism
- (of an infection) caused by any microorganism that is harmless to a healthy person but debilitates a person whose immune system has been weakened by disease or drug treatment
