/ Dictionary / Index P placebo effect: Meaning and Definition of Find definitions for: pla•ce'bo effect" Pronunciation: (plu-sē'bō), [key] a reaction to a placebo manifested by a lessening of symptoms or the production of anticipated side effects. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. placebo place card Related Content Daily Word Quiz: fervor Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language