Pronunciation (UK) IPA (key): /pləˈsiː.bəʊ/ (US) (Canada) IPA (key): /pləˈsi.boʊ/ (AU) IPA (key): /pləˈsiː.bəʉ/ Audio (UK)(file) Noun Singular placebo Plural placebos or placeboes (medicine) Placebo is a dummy medicine containing no active ingredients.Wikiwand - on Seamless Wikipedia browsing. On steroids.Remove ads