placebo effect

American

[pluh-see-boh] / pləˈsi boʊ /

noun

a reaction to a placebo manifested by a lessening of symptoms or the production of anticipated side effects.

placebo effect British

noun

med a positive therapeutic effect claimed by a patient after receiving a placebo believed by him to be an active drug See control group

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of placebo effect

First recorded in 1945–50

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

placebo effect

He dismisses concerns about its effectiveness, including suggestions that alleviated symptoms could be due to a placebo effect.

From BBC ● Sep. 12, 2026

"You can shape a treatment to fit the belief system without explicitly endorsing it," French said, conceding an exorcism might even have a beneficial placebo effect in some cases.

From Barron's ● Jul. 19, 2026

The other half received a sham treatment designed to control for the placebo effect.

From Science Daily ● May 22, 2026

They point to studies suggesting a strong caregiver placebo effect, with the only real change being the owner’s perception of their pet’s condition.

From The Wall Street Journal ● May 17, 2026

It must have been a placebo effect, but it was a great placebo effect.

From "It’s Kind of a Funny Story" by Ned Vizzini

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023