the eldest son in a family

an adopted son or godson in a traditional context, typically involving a formal recognition of the relationship without legal adoption

a child born after the death of their father

(xiehouyu) to have no hope left; describes a situation with no future prospects, referring to the traditional belief that a widow who loses her only son has no one left to support her in old age

(slang) A term of abuse used to call someone a bastard or a son of a bitch; originally referred to a man who ran a brothel or a cuckold.