What is the meaning of the word "oak leaf cluster"?

Definitions:

  1. A United States military decoration consisting of bronze or silver leaves and acorns awarded to anyone who has won a given medal before. copy to clipboard NOUN
    • During his service, he achieved the rank of captain and was awarded the Army Commendation Medal with Oak Leaf Cluster. copy to clipboard
  2. U.S military decoration in the form of a small bronze twig bearing four oak leaves and three acorns, worn on the ribbon of another decoration for valor, wounds, or distinguished service to signify a second award of the same medal. copy to clipboard NOUN
    • A Silver Star with 28 Oak Leaf Clusters signifies 29 awards of the medal, one that is very, very difficult to earn. copy to clipboard

Synonyms: