The Illuminatus! Trilogy is a series of three novels by American writers Robert Shea and Robert Anton Wilson, first published in 1975. The trilogy is a satirical, postmodern, science fiction–influenced adventure story; a drug-, sex-, and magic-laden trek through a number of conspiracy theories, both historical and imaginary, related to the authors' version of the Illuminati. The narrative often switches between third- and first-person perspectives in a nonlinear narrative. It is thematically dense, covering topics like counterculture, numerology, and Discordianism.

"Fnord" is a word coined in 1965 by Kerry Thornley and Greg Hill in the Discordian religious text Principia Discordia. It entered into popular culture after appearing in The Illuminatus! Trilogy (1975) of novels written by Robert Shea and Robert Anton Wilson. Here, the interjection "fnord" is given hypnotic power over the unenlightened, and children in grade school are taught to be unable to see the word consciously. For the rest of their lives, every appearance of the word subconsciously generates a feeling of unease and confusion which prevents rational consideration of the text in which it appears.