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

This has led to rampant speculation among members of the public, experts, and lawmakers, sometimes even turning to outlandish conspiracy theories, to explain the phenomenon. —Thomas G. Moukawsher, Newsweek, 17 Dec. 2024

According to Cao, stans today create their own cultural moments (memes, conspiracy theories, fan edits) and have created communities that bring likeminded peers together online. —Marilyn La Jeunesse, Parents, 16 Dec. 2024

And on TikTok, all of these conspiracy theories and more are shared in videos viewed tens of millions of times and set to songs like Britney Spears’ Criminal. —David Gilbert, WIRED, 16 Dec. 2024

For years, right-wing media personalities and politicians have promoted the conspiracy theory. —Ivana Saric, Axios, 13 Dec. 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