A rubber stamp is a small tool with a raised design or letters on its surface that you press into an ink pad and then onto paper, leaving behind a clear image or text. Teachers use rubber stamps to mark homework with stars or smiley faces. Libraries use them to mark due dates on checkout cards. Office workers might stamp “PAID” or “RECEIVED” on documents.

The term also has a second, more critical meaning: when someone acts as a rubber stamp, they automatically approve whatever comes before them without really thinking about it or asking questions. Imagine a school council that just says yes to every idea the principal suggests, never discussing whether the ideas are actually good. They're rubber-stamping decisions instead of carefully considering them.

When a committee rubber-stamps a proposal, they're not examining it thoughtfully. The phrase suggests automatic approval, like mechanically stamping papers over and over.