means A traditional story, often involving gods or origins, that a culture tells to explain the world or itself — and, by extension, any widely held but false belief.

from From Greek 'mythos,' meaning simply a word, a speech, a tale — anything spoken aloud. To the early Greeks a mythos was just a story told, sitting beside 'logos' (reasoned account); over time mythos drifted toward the narrative that wasn't strictly argued or proven. It reached English in the 19th century via Latin 'mythus,' arriving rather late for so ancient an idea.