'Bó dào wú ér' is a classical Chinese idiom referring to the tragic situation of a morally upright, benevolent person who remains childless despite their virtue and good deeds. It originates from the story of Bo Dao, a Jin dynasty official renowned for his integrity and filial piety; when forced to choose between saving his nephew or his own infant son during a crisis, he chose the nephew — and later died without heirs. The phrase thus evokes deep sympathy and philosophical reflection on fate versus moral reward.

The four characters combine literally as 'Bo Dao (a proper name) + no + child', but function as a fixed noun phrase expressing irony and pathos. It appears mainly in literary, historical, or reflective contexts — never in casual speech — and often conveys melancholy, resignation, or admiration mixed with sorrow. Modern usage is rare and highly stylized, typically found in essays, poetry, or formal commentary about virtue, sacrifice, or life’s injustices.