What does the word stopper mean?

Usage examples for stopper

  1. He had just restored the stopper to the spirit decanter, saying to himself, " Nice, thoughtful little girl!" – King of the Castle by George Manville Fenn
  2. Sue would put a stopper on it at once. – Leonore Stubbs by L. B. Walford
  3. True, he knew the secret of the crystal stopper. – The Crystal Stopper by Maurice LeBlanc