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

Similar clinical studies showed that nearly 7 out of 10 people who took TEPEZZA saw improvements in double vision, compared to 3 out of 10 who took placebo. —Lauryn Higgins, Flow Space, 27 May 2026

In the study, 648 adults with Parkinson’s were randomized to receive either a placebo or a pill targeting a protein called LRRK2. —Ed Silverman, STAT, 22 May 2026

For the study, more than 2,300 adults with obesity received retatrutide in doses of 4, 9, or 12 milligrams (mg) or a placebo. —Emily Kay Votruba, EverydayHealth.com, 21 May 2026

Lilly also said that compared with placebo, patients taking retatrutide also had more reports of unusual or uncomfortable skin sensations and urinary tract infections. —Berkeley Lovelace Jr, NBC news, 21 May 2026

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)