Adjective

1. Of a person, organisation, or process, making decisions or approving matters routinely or without real power, as rubber stamp politics, a rubber stamp committee.

Noun

1. A piece of rubber or similar material with a design or text carved or molded for the purpose of transferring ink or dye to imprint that design on another object.

   The library had a rubber stamp to imprint the due date.

2. A person or organisation who approves, routinely or as a formality, matters decided by some other person or organisation.

Verb

1. to process, approve or decide matters routinely rather than through careful consideration

   They usually just rubber stamp orders under $100.