Definition of rubber stamp:
(n) :
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; when used attributively with another noun: Approving or deciding matters routinely or powerlessly rather than through careful consideration; as, rubberstamp politics
"the library had a rubber stamp to imprint the due date."
"they usually just rubber stamp orders under $100."