placebo

pla·ce·bo

noun \plə-ˈsē-(ˌ)bō\

plural pla·ce·bos

Definition of PLACEBO

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)