plural placebos
1
a
: 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

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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Participants were randomly assigned to receive either the vaccine with pembrolizumab or placebo injections alongside the immune treatment. — Mike McRae 25, New Atlas, 26 Oct. 2026 And a 2013 analysis found modest reductions in joint pain among postmenopausal women receiving estrogen compared with placebo. — Cheyenne Buckingham, Washington Post, 24 Oct. 2026 Two years later, 82% of the patients who received both the new vaccine and the immunotherapy hadn’t had a recurrence, compared with 70% in the immunotherapy plus placebo group. — David Cox, NBC news, 23 Oct. 2026 First, the study did not include a control group receiving a mock or placebo procedure. — Khloe Quill, FOXNews.com, 23 Oct. 2026 See All Example Sentences for placebo

Word History

Etymology

Latin, I shall please

First Known Use

1785, in the meaning defined at sense 1a

Time Traveler
The first known use of placebo was in 1785

Browse Nearby Words

Cite this Entry

“Placebo.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/placebo. Accessed 27 Oct. 2026.

Kids Definition

plural placebos
1
: a medicine that usually has no effect on a disease and is prescribed by a doctor for the mental relief it offers a patient
2
something that is meant to soothe
Etymology

from Latin placebo "I shall please"

Medical Definition

plural placebos
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)
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