Placebo effect n. (Med.) A reaction by a patient who receives a placebo (2), in which the symptoms of illness are lessened or an anticipated effect is experienced. Because the placebo (2) itself has no pharmacological activity, this reaction is mediated by the expectations of the patient receiving the placebo (2); the reaction is considered as an example of the power of suggestion. Note: Dramatic subjective effects such as relief of discomfort or pain are sometimes observed due to administration of a placebo, but in some cases measurable physiological effects may also be observed.
Collaborative International Dictionary of English 0.48