delusion

1 a conception or image created by the imagination and having no objective reality her idea that her new man is a long lost prince is surely just a delusion Synonyms chimera, conceit, daydream, fantasy, dream, fancy, figment, hallucination, illusion, nonentity, phantasm (also fantasm), pipe dream, unreality, visionRelated Words ignis fatuus, mirage, will-o'-the-wisp; brainchild, idea; concoction, fable, fabrication, fiction, invention; envisaging, imaging, visualization; cloud-cuckoo-land, cloudland, Shangri-la, utopia; daymare, nightmareNear Antonyms actuality, fact, reality

2 a false idea or belief he appears to suffer from the delusion that he's the best reporter in the business Synonyms fallacy, error, falsehood, falsity, hallucination, illusion, misbelief, misconception, myth, old wives' tale, untruthRelated Words factoid; superstition; fiction, pretense (or pretence); distortion, inaccuracy, misapprehension, miscomprehension, misinterpretation, misjudgment, misperception, misunderstanding; misinformation, misknowledge, misreport, misrepresentation, misstatement; sophism, sophistry; fib, half-truth, lie, story, taleAntonyms truth, verity