placebo

American  

[pluh-see-boh, plah-chay-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

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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”

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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

Despite the encouraging pattern in depressive symptoms among participants consuming blueberries, the researchers found no statistically significant difference in mood improvements between the blueberry and placebo groups.

From Science Daily ● Oct. 18, 2026

To investigate, the Yale team conducted an experiment in which participants took a pill containing either hydrocortisone, a form of cortisol, or an inactive placebo.

From Science Daily ● Oct. 16, 2026

Each person completed the experiment twice, once after receiving hydrocortisone and once after receiving the placebo.

From Science Daily ● Oct. 16, 2026

Visceral fat decreased among participants receiving the experimental injection but increased among those given the placebo.

From Science Daily ● Oct. 11, 2026

As it happens, Denis Papin, who had qualified as a doctor, was the first to describe the placebo and the placebo effect, in a letter to Leibniz, 11 or 12 August 1704.

From "The Invention of Science" by David Wootton

The third group received the same inactive pills but was openly informed that the pills were placebos that could still trigger beneficial mind-body responses.

From Science Daily ● Jun. 25, 2026

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

Since the ’70s, many other studies have confirmed that placebos can activate opioid receptors, as well as dopamine receptors, which are part of the body’s internal reward system.

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

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