conspiracy theorist

• (Received Pronunciation) IPA^(key): /kənˈspɪɹ.ə.si ˌθɪəɹɪst/
• (General American) IPA^(key): /kənˈspɪɹ.ə.si ˌθi.ɚ.əst/, /- ˌθɪɚ.əst/, /- ˌθɪɚ.ɪst/
• (General Australian) IPA^(key): /kənˈspɪɹ.ə.siː ˌθɪə.ɹəst/, /- ˌθiː.ə.ɹəst/
• (New Zealand) IPA^(key): /kɘnˈspɘɹ.ɘ.siː ˌθiə.ɹɘst/, /- ˌθiː.ɘ.ɹɘst/

conspiracy theorist (plural conspiracy theorists)

1. One who believes in, follows, or advances a conspiracy theory.

   Mike's a conspiracy theorist; he thinks NASA faked the moon landings.

   • 1993, Christopher Hitchens, For the Sake of Argument:

     And you may have noticed that those who are too quick to shout 'conspiracy theorist' are equally swift, when consequences for authority and consensus impend, to look serious and say 'It's more complicated than that.' These have become standard damage-control reflexes.

• conspiratard (slang, derogatory), conspiracist, conspirophile (rare)
• tinfoil hatter (slang, derogatory), truther
• conspiracy analyst (not pejorative)

• (US) crackpot (slang)
• (UK) crank (slang)