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

In a Phase 3 trial of people with post-bariatric hypoglycemia, or PBH, those taking the drug experienced a 55% reduction in the rate of serious low blood sugar events compared with those on placebo. — Elaine Chen, STAT, 18 Aug. 2026

Fifty-one healthy adults were randomly given either a fidget ring or a placebo ring to wear for a week. — Samantha Agate, Sacbee.com, 17 Aug. 2026

Understand the facts In some trials, some participants are given a new drug or therapy that’s being investigated while others receive a placebo with no physical effect. — Michelle Andrews, USA Today, 15 Aug. 2026

Bruno says the findings highlight the need for prospective clinical trials, meaning women would be randomized to receive either hormone therapy or a placebo, and then followed over time to see how outcomes differ. — Tom Gavin, EverydayHealth.com, 12 Aug. 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)