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

On Saturday, Janet falsely claimed to The Guardian that Harris, 59, isn't Black, repeating a right-wing conspiracy theory. —Marina Watts, Peoplemag, 22 Sep. 2024

Jackson appeared to be parroting a right-wing conspiracy theory perpetuated by Harris’ presidential opponent Donald Trump. —Glenn Garner, Deadline, 22 Sep. 2024

Dominion and Smartmatic, two companies that manufacture voting machines, have been linked to the baseless conspiracy theories and have taken those claims to court. —Ty Roush, Forbes, 20 Sep. 2024

The pronoun in question referred to Springfield’s Haitian community, and the claim repeated a conspiracy theory that had been circulating on the right-wing Internet, channelling the centuries-long persecution of Haitians and West Indians. —Lauren Michele Jackson, The New Yorker, 19 Sep. 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