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 burger has been sold at Petco Park ever since, with the same recipe, despite the online conspiracy theory that its three onion rings represented the Dodgers’ three World Series championship rings this decade. — Bill Shaikin, Los Angeles Times, 26 June 2026

Prolonged uncertainty feeds conspiracy theories. — Sun Sentinel Editorial Board, Sun Sentinel, 25 June 2026

Dominion sued the businessman in 2021, alleging that Lindell knew there was no evidence to support his election conspiracy theories, but used the lies to sell pillows. — Aki Nace, CBS News, 24 June 2026

Georgia voting machines have been the subject of conspiracy theories, which manufacturer Dominion Voting Systems fought vigorously in court. — ABC News, 23 June 2026

Word History

First Known Use

1863, in the meaning defined above

Rhymes for conspiracy theory

• beery
• bleary
• cheery
• cirri
• dearie
• deary
• dreary
• eerie
• kiri
• leary
• leery
• peery

Kids Definition

conspiracy theory

noun

: a theory that explains an event or situation as being the result of a secret plot

conspiracy theorist noun