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

But the assassination attempt was widely discussed on Chinese social media, where even high-profile academics propagated conspiracy theories of the gunman’s motives. —Stephanie Yang, Los Angeles Times, 17 July 2024

In Hollywood, where Jewish success has inspired antisemitic conspiracy theories for a hundred years, Jews in the industry have been on high alert. —Michael Schulman, The New Yorker, 17 July 2024

Reuters Republican presidential nominee Donald Trump repeated false conspiracy theories about childhood vaccinations during a recent call with the third-party presidential candidate Robert F. Kennedy Jr., according to a video of the call leaked Tuesday. —Kevin Breuninger, CNBC, 16 July 2024

Trump’s rhetoric has echoed language in far-right conspiracy theories linked to mass shootings in El Paso, a synagogue in Pennsylvania and the wider mobilization of armed far-right White supremacists. —Ishaan Tharoor, Washington Post, 15 July 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