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

Not only has Russia exported its firehose strategy abroad in efforts to destabilize elections in the West, but Trump and MAGA-Republicans have adopted it as their go-to strategy for normalizing lies and conspiracy theories in the United States. —Michiko Kakutani, TIME, 6 June 2024

The media outlet has since become a forceful presence among conservative news organizations, known for spreading conspiracy theories, particularly on social media, and as a staunch supporter of former President Trump and his allies. —Stacy Perman, Los Angeles Times, 4 June 2024

Gaetz then hit back arguing that by refusing to immediately hand over any such documents, the Justice Department is only fomenting more conspiracy theories. —Alexander Mallin, ABC News, 4 June 2024

The Washington Post/The Washington Post via Getty Im/The Washington Post That questioning feeds into a conspiracy theory that EcoHealth was somehow doing Fauci’s bidding to seed the pandemic. —Geoff Brumfiel, NPR, 2 June 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