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1630s, "huge wagon bearing an image of the god Krishna," especially that at the town of Puri, drawn annually in procession in which (apocryphally) devotees allowed themselves to be crushed under its wheels in sacrifice. Altered from Jaggernaut, a title of Krishna (an incarnation of Vishnu), from Hindi Jagannath, literally "lord of the world," from Sanskrit jagat "world" (literally "moving," present participle of *jagati "he goes," from PIE *gwa- "to go, come" (see come (v.)) + natha-s "lord, master," from nathate "he helps, protects," from PIE *na- "to help." The first European description of the festival is by Friar Odoric (c.1321). Figurative sense of "anything that demands blind devotion or merciless sacrifice" is from 1854.
A deity in Hinduism, considered a deliverer from sin. His image is carried on a large wagon in an annual procession in India, and according to legend the wagon crushed worshipers who threw themselves under it.
Note: A force, an idea, or a system of beliefs that overcomes opposition — especially if it does so ruthlessly — is called a “juggernaut.”