placebo noun definition in Medication topic from the Oxford Advanced Learner's Dictionary

placebo

 noun: Medication topic
a substance that has no physical effects, given to patients who do not need medicine but think that they do, or used when testing new drugs the placebo effect (= the effect of taking a placebo and feeling better) Half of the people taking part in the experiment were given a placebo. The placebo effect means that any treatment will improve patients merely because they want to recover.