gavel
Definitions
A small mallet with which an auctioneer, a judge, or the chair of a meeting hits a surface to call for attention or order.
A mallet used by a presiding officer to signal the beginning or end of proceedings.
Examples
The judge struck the gavel against the wooden block to restore order in the courtroom.
After the auctioneer brought down his gavel, the rare painting was officially sold to the highest bidder.