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

Sellers endorsed Navarro for the seat in September, citing the spread of unfounded election conspiracy theories that have cast doubt on outcomes in recent election cycles. —Sasha Hupka, The Arizona Republic, 5 Nov. 2024

In 2022, a man who has cited a variety of conspiracy theories broke into Pelosi's San Francisco house looking for her. —Liam Quinn, People.com, 5 Nov. 2024

The 86 jurisdictions that the Justice Department will send monitors to on Tuesday include Maricopa County, Arizona and Fulton County, Georgia, which in 2020 became the center of election conspiracy theories spread by Trump and other Republicans. —Chris Morris, Fortune, 5 Nov. 2024

It's been the subject of long-running conspiracy theories. —Cybele Mayes-Osterman, USA TODAY, 4 Nov. 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