How would you define a belief that is considered false or misleading?

The term that defines a belief considered false or misleading is "fallacious." This word is often associated with arguments or reasoning that appear to be sound on the surface but contain errors or misleading components upon closer examination. A fallacious belief lacks substantiation or is based on false premises, making it an unreliable foundation for conclusions or actions.

Other terms provided do not convey the same meaning. For instance, "plausible" refers to something that seems reasonable or probable, rather than being necessarily false or misleading. "Pertinent" describes something relevant or applicable to a matter at hand, which has no relation to the truthfulness of a belief. "Eccentric" pertains to something that is unconventional or unusual, which does not imply that the belief is false or misleading in the context of its truth value. Thus, "fallacious" is the accurate choice to define a belief that is unsupported and misleading.