placebo

noun

pla·​ce·​bo plə-ˈsē-(ˌ)bō 

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

The antibody reduced eczema severity by 71% over 16 weeks, compared to about 34% in the placebo group. —Scott Schnipper, CNBC, 7 July 2025

The placebo group also experienced worsening psychiatric symptoms. —New Atlas, 6 July 2025

In a 2019 randomized, double-blind study involving adults with chronic stress, those who took ashwagandha extract for 60 days had significantly lower cortisol levels compared to the placebo group (participants taking a substance of no therapeutic value). —Sarah Jividen, Verywell Health, 26 June 2025

Those who got the highest doses (up to 60 mg) lost up to 24.3% pounds after 36 weeks, compared to just 1.1% for the placebo group, per the release. —Melissa Rudy, FOXNews.com, 23 June 2025

Word History

Etymology

Latin, I shall please

First Known Use

1785, in the meaning defined at sense 1a

Phrases Containing placebo

• placebo effect

Kids Definition

placebo

noun

pla·​ce·​bo plə-ˈsē-bō 

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

placebo

noun

pla·​ce·​bo plə-ˈsē-(ˌ)bō 

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)