Wu Mengzi (吳孟子) was the name that Duke Zhao of Lu (魯昭公) gave to his wife to mask the fact that he had violated a serious social taboo by marrying a woman with the same clan name (姬/Jī) as his own.
Wu Mengzi literally means “Mengzi of Wu”, which is the name of the state that she came from. Even though the duke and his wife were not related by blood, the duke was criticized for his failure to respect the rites (禮/lǐ) by marrying her.
Appearances in the Analects of Confucius
Book 7, Chapter XXX
Chen Sibai asked: “Did Duke Zhao understand the rites?” Confucius said: “Yes, he understood the rites.” Confucius withdrew. With a bow, Chen invited Wuma Qi to come forward and said to him: “I have heard it said that a true leader is never biased. But isn’t your master biased after all? The Duke took a wife from the state of Wu, but since she belonged to his own clan he changed her name to Wu Mengzi. If the Duke understood the rites, who doesn’t understand them?” Wuma Qi reported this to Confucius. Confucius said: “I am fortunate indeed: whenever I make a mistake, there is always someone on hand to let me know about it.”