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

People taking the twice-daily pill also had slower brain shrinkage — particularly in the hippocampus, which controls memory and thinking, the atrophy was about 18% less than those taking the placebo. —Melissa Rudy, FOXNews.com, 30 Oct. 2025

In the hippocampus, for example, participants who got ALZ-801 experienced about 18% less atrophy than those who got a placebo. —Jon Hamilton, NPR, 29 Oct. 2025

However, Lowe wants people to know that patients aren’t neglected when they’re given a placebo treatment. —Alexis Kayser, MSNBC Newsweek, 29 Oct. 2025

By comparison, people who took a placebo had a 47% reduction in hot flashes. —Korin Miller, SELF, 27 Oct. 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)