"close growth of hair on the chin and lower face, normally characteristic of an adult male" (that of the upper lip being distinguished in Modern English as the mustache), Old English beard "beard," from Proto-Germanic *bard (source also of Old Frisian berd, Middle Dutch baert, Old High German bart, German bart), said ...

Why is a person called a beard?

A “beard” is an antiquated slang term for someone whose social presence serves to mask aspects of someone else's true self from the public. In the early days of queer culture, a “beard” was a wife, girlfriend or female companion who acted (wittingly or not) as social cover for a closeted gay man.

What does a beard mean in British slang?

A beard is defined as a woman who dates, or marries, a gay man to provide cover for the man's homosexuality. The term also applies to a man who does the same for a lesbian woman.