conspiracy theory

noun

plural conspiracy theories

: a theory that explains an event or set of circumstances as the result of a secret plot by usually powerful conspirators

the conspiracy theories surrounding Kennedy's assassination

also : a theory asserting that a secret of great importance is being kept from the public

… is best known for … his conspiracy theory that a secret cabal of reptilian humanoids is running the world.

—Simon Little

… has often been criticized for promoting conspiracy theories such as "birtherism," the theory that President Obama was not born in the U.S.

—Grace Segers

Examples of conspiracy theory in a Sentence

Conspiracy theories sprung up soon after the leader's assassination.

Recent Examples on the Web

Its founder, Henry Ford, was vocally antisemitic and spread conspiracy theories about the Jewish people. —George Monastiriakos, Newsweek, 30 Dec. 2024

In an era rife with conspiracy theories and subterfuge, how much of those forces are products of our own doing, perhaps our imagining? —Dana Feldman, Forbes, 30 Dec. 2024

Various conspiracy theories that had been floating around the fringes of American culture for decades became incorporated into the movement. —Jude Joffe-Block, NPR, 30 Dec. 2024

The New Jersey Drone Hunters Without much guidance or information from the government, conspiracy theories surrounding the mystery drones supposedly hovering over the eastern seaboard have gotten out of control. —Makena Kelly, WIRED, 19 Dec. 2024

Word History

First Known Use

1863, in the meaning defined above

Kids Definition

conspiracy theory

noun

: a theory that explains an event or situation as being the result of a secret plot

conspiracy theorist noun