placebo

American  

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

noun

placebos, plural placeboes plural

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.

Other Word Forms

Noun Inflected Forms

• placeboes
  plural
• placebos
  plural

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

See Examples For:

placebo placebos

However, it failed to meet the primary efficacy endpoint compared with placebo when treating transthyretin amyloid cardiomyopathy.

From The Wall Street Journal ● Jul. 9, 2026

Half of the participants were given the MenB vaccine while the other half were given a placebo.

From BBC ● Jul. 8, 2026

People who took Wegovy tablets lost on average 13.61% of their body weight, compared with 2.18% in the placebo group.

From BBC ● Jul. 6, 2026

In one study, participants who took five grams of creatine each day alongside the antidepressant escitalopram experienced greater reductions in depressive symptoms after eight weeks than those receiving escitalopram with a placebo.

From Science Daily ● Jun. 30, 2026

Modern trials of the efficacy of therapies depend on the idea that an effective therapy must perform better than a placebo.

From "The Invention of Science" by David Wootton

The U-turns mark a broader retreat from demands, pushed under former FDA vaccines and biotech drugs division leader Vinay Prasad, that rare-disease drugmakers test their experimental medicines against placebos to make sure the drugs work.

From The Wall Street Journal ● Jun. 22, 2026

These sessions used an "open-label placebo" approach, meaning participants were aware that some practices were presented as placebos.

From Science Daily ● Apr. 7, 2026

It was seen as not only socially acceptable but humane to prescribe placebos.

From Slate ● Jan. 30, 2026

While studies showed that Sarepta’s Amondys 45 and Vyondys 53 treatments for Duchenne muscular dystrophy worked better than placebos, the company said the results did not reach statistical significance.

From MarketWatch ● Nov. 3, 2025

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