placebo

American  

[pluh-see-boh, plah-chey-boh] / pləˈsi boʊ, plɑˈtʃeɪ boʊ /

noun

plural

placebos, placeboes

1. Medicine/Medical, Pharmacology.

   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. Roman Catholic Church. 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.

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placebo British  

/ pləˈsiːbəʊ /

noun

1. med 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 for the psychological benefit to the patient through his believing he is receiving treatment See also control group placebo effect

2. something said or done to please or humour another

3. RC Church a traditional name for the vespers of the office for the dead

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placebo Scientific  

/ plə-sē′bō /

1. A substance containing no medication and prescribed to reinforce a patient's expectation of getting well or used as a control in a clinical research trial to determine the effectiveness of a potential new drug.

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placebo Cultural  

1. A substance containing no active drug, administered to a patient participating in a medical experiment as a control.

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Discover More

Those receiving a placebo often get better, a phenomenon known as the placebo effect.

Etymology

Origin of placebo

1175–1225 placebo for def. 2; 1775–85 placebo for def. 1; Middle English < Latin placēbō “I shall be pleasing, acceptable”

Explanation

A patient's symptoms sometimes disappear just because they believe that they are being treated. Even when doctors give them a biologically inactive drug, otherwise known as a placebo, the patients swear they are cured. In clinical drug-trials, to rule out what is called the placebo effect, scientists give half of the trial participants a placebo. If a government replaces food stamps with a coloring book give-away, it might be dismissed by child advocates as nothing more than a placebo. Placēbō is Latin for "I'll please (you)," in other words, I'll keep you happy, even though I'm just giving you a placebo.

Example Sentences

The team also plans to examine how different elements of the retreat, including meditation, reconceptualization, and open-label placebo healing, contribute individually and together.

From Science Daily • Apr. 7, 2026

A drug also needs to be proven to work better than a placebo.

From Slate • Mar. 30, 2026

The company said patients who were on the highest dose lost 15.3% of their weight while those in the placebo group lost 2.6%.

From The Wall Street Journal • Mar. 19, 2026

Huynh said he was surprised at how few placebo patients in Structure’s study gained weight, and suggested investors wait to see Structure’s Phase 3 results.

From Barron's • Mar. 16, 2026

If placebo effects were this good, they should just make placebos the way to treat depression—maybe that’s what they did; maybe Zoloft was cornstarch.

From "It’s Kind of a Funny Story" by Ned Vizzini