外傳

to tell others (a secret) / to divulge to an outsider / to be rumored

unofficial biography (as opposed to official dynastic biography)

outside / in addition / foreign / external

to pass on / to spread / to transmit / to infect / to transfer / to circulate / to conduct (electricity)

biography / historical narrative / commentaries / relay station

Don't spread abroad the shame of the family, don't believe rumors lightly. (idiom) / Don't wash your dirty linen in public, don't listen to others' gossip.

Apocrypha / biography external to the classics

lit. family shames must not be spread abroad (idiom); fig. don't wash your dirty linen in public