The story
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: An image of a man perceived in the dark maria (plains or "seas") and light highlands or other features of the Moon, originally regarded as a man with a burden on his back or accompanied by a small dog, and now more commonly as a man's face in the full moon or his profile in a crescent moon; hence, an imaginary man thought to be living on the Moon. Full definition →
Etymology from Wiktionary, CC BY-SA 4.0.