placebo: Meaning and Definition of

pla•ce•bo

1. a substance having no pharmacological effect but given merely to satisfy a patient who supposes it to be a medicine.
2. a substance having no pharmacological effect but administered as a control in testing experimentally or clinically the efficacy of a biologically active preparation.
2. the vespers of the office for the dead: so called from the initial word of the first antiphon, taken from Psalm 114:9 of the Vulgate.