Modern usage: solitary elderly person, especially in welfare contexts ('
五保孤老' — childless elderly in the rural Five-Guarantees system). Historical/Ming-Qing slang: a courtesan's regular customer (a man she relied on the way an old woman relies on family) — you'll see this sense in 《
金瓶梅》 and other late-imperial novels, but the modern social-services sense dominates.
