Real Dictionary

placebo in American English
the first antiphon of the vespers for the dead, beginning with the word placebo
noun: a substance having no pharmacological effect but given merely to satisfy a patient who supposes it to be a medicine

placebo in British English
noun: an inactive substance or other sham form of therapy administered to a patient usually to compare its effects with those of a real drug or treatment, but sometimes to provide psychological benefit to patients by allowing them to believe they are receiving

placebo in the Pharmaceutical Industry
noun: A placebo is a substance with no chemical effects given to a patient instead of a drug. A placebo is usually used to compare its effects with those of a real drug, but sometimes it is given for a patient's psychological benefit.