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

Local and national news The man who set himself on fire outside Trump’s trial had reportedly spouted conspiracy theories. —Andrew J. Campa, Los Angeles Times, 21 Apr. 2024

In the United States, the most popular conspiracy theory saw Fast and Furious as a plot by President Barack Obama’s administration to rein- state an assault rifle ban and implement new gun control measures. —Ieva Jusionyte, Rolling Stone, 16 Apr. 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