age before beauty

Please after you read the following, if you know any other definition and/or an idea write it ( please mention the reference if it is there )

according to THE Dictionary of English Idioms & Idiomatic Expressions
the expression AGE BEFORE BEAUTY is used in English language by some one in a way of allowing an older person to do something first, though often in a slightly sarcastic way.

Historically the expression AGE BEFORE BEAUTY started life in the late 19th century probably as a graceful way for an older woman to acknowledge the courtesy of a younger one who stands aside to let her take precedence in entering a room. It soon came to be a gallantry of an older man to a girl, and to be used jocularly and maliciously between other pairs.

I think that definition says it all. What are you trying to find out?

you are absolutely right.

but I’m trying to find out the definition from other sources such as ( LONG MAN,Oxford. Miriam Webster,and others.

thanks in advance