A traditional notion that is obstinately held although it is unreasonable.

Roget 495: error, fallacy; misconception, misapprehension, misstanding^†, misunderstanding; inexactness etc. adj.; laxity; misconstruction etc. (misinterpretation) 523; miscomputation etc. (misjudgment) 481; non sequitur etc. 477; mis-statement, mis-report; mumpsimus^†.    mistake; miss, fault, blunder, quiproquo, cross purposes, oversight, misprint, erratum, corrigendum, slip, blot, flaw, loose thread; trip, stumble etc. (failure) 732; botchery etc. (want of skill) 699^†; slip of the tongue, slip of the lip, Freudian slip; slip of the pen; lapsus linguae [Lat.], clerical error; bull etc. (absurdity) 497; haplography^†.    illusion, delusion; snare; false impression, false idea; bubble; self-decit, self-deception; mists of error.    heresy etc. (heterodoxy) 984; hallucination etc. (insanity) 503; false light etc. (fallacy of vision) 443; dream etc. (fancy) 515; fable etc. (untruth) 546; bias etc. (misjudgment) 481; misleading etc. v.. ... show more