pla·ce·bo | \ plə-ˈsē-(ˌ)bō \
plural placebos

Definition of placebo 

1a : a usually pharmacologically inert preparation prescribed more for the mental relief of the patient than for its actual effect on a disorder

b : an inert or innocuous substance used especially in controlled experiments testing the efficacy of another substance (such as a drug)

2 : something tending to soothe

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Did You Know?

Doctors doing research on new treatments for disease often give one group a placebo while a second group takes the new medication. Since those in the placebo group usually believe they're getting the real thing, their own hopeful attitude may bring about improvement in their condition. Thus, for the real drug to be considered effective, it must produce even better results than the placebo. Placebos have another use as well. A doctor who suspects that a patient's physical symptoms are psychologically produced may prescribe a placebo in the hope that mentally produced symptoms can also be mentally cured.

Examples of placebo in a Sentence

Recent Examples on the Web

The reduction in density in the shin bone was nearly half as large in women taking L. reuteri supplements as in those taking the placebo. Nicholas Bakalar, New York Times, "Probiotics May Be Good for Your Bones," 3 July 2018 In a three-year clinical trial, oncologist Dr. Maha Hussain found that enzalutamide resulted in a 71% lower risk of cancer spread or death compared to those taking the placebo. Renae Reints, Fortune, "New Treatment for Aggressive Prostate Cancer Shows 71% Lower Risk of Spread or Death," 28 June 2018 Allergan recalled one lot of Taytulla birth control pills sample packs after a packaging snafu put placebo capsules in slots meant for actual birth control capsules. David J. Neal, miamiherald, "Here's why these birth control pills don't work and have been recalled," 30 May 2018 The plan is to infuse mitochondria or a placebo solution into the coronary arteries of people having bypass surgery or — an even more dire situation for the heart — having both bypass and valve surgery. New York Times, "Dying Organs Restored to Life in Novel Experiments," 10 July 2018 Compared to young mice that had received placebo cells, the animals with the senescent cell transplants started to walk more slowly, and weren’t able to hang on to a rod as long or grip as strongly after a month. Alice Park, Time, "How Scientists Are Testing Cancer Drugs to Slow Down Aging," 9 July 2018 These are both a little pricey and may or may not have solid science behind them, but even a placebo works three out of 10 times. Houston Chronicle, "How to “live long and prosper”," 7 July 2018 The results, which appeared in The Lancet in 2001, showed that patients who applied the T4N5 developed significantly fewer cancerous and precancerous lesions than the placebo group. Robbie Gonzalez, WIRED, "DNA-Repairing Sunscreen: Legit or Not?," 2 July 2018 Experts say that lack of data is because pharmaceutical companies' big clinical trials comparing drug treatment to placebo were all done in women. Marie Mccullough,, "Updated osteoporosis screening guidelines cover only women. That could hurt men," 27 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'placebo.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of placebo

1785, in the meaning defined at sense 1a

History and Etymology for placebo

Latin, I shall please

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Statistics for placebo

Last Updated

1 Sep 2018

Look-up Popularity

Time Traveler for placebo

The first known use of placebo was in 1785

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More Definitions for placebo



English Language Learners Definition of placebo

medical : a pill or substance that is given to a patient like a drug but that has no physical effect on the patient


pla·ce·bo | \ plə-ˈsē-(ˌ)bō \
plural placebos

Medical Definition of placebo 

1 : a usually pharmacologically inert preparation prescribed more for the mental relief of the patient than for its actual effect on a disorder

2 : an inert or innocuous substance used especially in controlled experiments testing the efficacy of another substance (as a drug)

Keep scrolling for more

More from Merriam-Webster on placebo

Spanish Central: Translation of placebo

Nglish: Translation of placebo for Spanish Speakers

Britannica English: Translation of placebo for Arabic Speakers

Comments on placebo

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the setting in which something occurs

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