تعریف و معنای "[button|zip] {one's} [lip]"

What is the origin of the idiom "Button one's lip" and when to use it?

The idiom "Button one's lip" or "Button your lip" has its origin in the early 20th century. The word "button" here means to fasten or close, and "lip" refers to the mouth or lips. The idiom suggests the action of closing or fastening one's lips together, symbolizing keeping them shut and not speaking or revealing something. It is used to advise someone to remain silent or keep a secret. It This idiom can be used in various occasions, such as when someone is tempted to reveal classified information, when discussing private matters that should remain undisclosed, or when urging someone to refrain from sharing gossip or spreading rumors.