Definition of placebo in English:

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Pronunciation: /pləˈsēbō/

noun (plural placebos)

1A harmless pill, medicine, or procedure prescribed more for the psychological benefit to the patient than for any physiological effect: his Aunt Beatrice had been kept alive on sympathy and placebos for thirty years [as modifier]: placebo drugs
More example sentences
  • According to the report published in the British Medical Journal, 60 percent of medical professionals prescribe placebos to their patients.
  • According to a new study by Israeli researchers, most doctors prescribe placebos to their patients, and in most of these cases, the patients are told they are receiving real medication.
  • And, if some patients benefit from placebos, and they are not harmed, I guess I can live with that.
1.1A substance that has no therapeutic effect, used as a control in testing new drugs.
Example sentences
  • All placebo controlled trials were positive and all comparative trials indicated equivalence with other active therapies.
  • That one doesn't get answered as often as it should, because the FDA generally only requires testing against placebo.
  • The practice of testing new medicines against placebo, rather than against the best treatment available, has contributed to a general lack of knowledge.
1.2A measure designed merely to calm or please someone.
Example sentences
  • It's interesting that the broken crosswalk buttons were not originally designed to act as placebos (presumably).
  • The stock markets, leisure travel, and all the other industries affected are relying on the sum of all these measures, including the placebos, to recover.
  • There is some debate as to whether an argon suit inflation system keeps you warm, or merely acts as a placebo i.e. making you believe that you're warmer!


Late 18th century: from Latin, literally 'I shall please', from placere 'to please'.

  • In Latin placebo means ‘I shall be acceptable or pleasing’. Doctors have probably always prescribed some drugs just to keep a patient happy, and used the term placebo for these as far back as the late 18th century. Researchers testing new drugs give some participants substances with no therapeutic effect to compare their reactions to those who have genuinely been treated: such a substance is also a placebo. Results may be confused, though, by the placebo effect, first identified in the early 1950s, in which the person's belief in the treatment brings about beneficial effects that have nothing to do with the properties of the placebo they have taken. Placid (early 17th century) comes from the same Latin root, along with words under please.

Words that rhyme with placebo

gazebo, grebo

For editors and proofreaders

Syllabification: pla·ce·bo

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