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

Recently, she was criticized for not taking sides in the conflict between Owens and Kirk’s widow, Erika, who had asked Owens to stop spreading conspiracy theories about Charlie’s murder. —Kimberly Nordyke, HollywoodReporter, 23 Dec. 2025

In recent months, Owens has been sharing multiple conspiracy theories about who was responsible for Charlie's death, which has allegedly caused a rift between the two, per CNN. —Becca Longmire, PEOPLE, 22 Dec. 2025

Her death was ruled a probable suicide, though conspiracy theories surround the case to this day. —Emily Trainham, FOXNews.com, 21 Dec. 2025

The flub came as Candace Owens, a right-wing podcaster and former Turning Point contributor, has spread outlandish conspiracy theories about Charlie Kirk’s murder. —Stephanie Murray, AZCentral.com, 21 Dec. 2025

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