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

The company’s public relations crisis has also been marred by conspiracy theories as the result of the deaths of multiple corporate whistleblowers who have spoken out about safety issues at the company. —Lucas Ropek / Gizmodo, Quartz, 7 May 2024

The notion that the FBI orchestrated the Jan. 6 riot is a conspiracy theory that lacks evidence, The Associated Press has reported. —Joe Marusak, Charlotte Observer, 5 May 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