What is another word for oak apple?
Pronunciation: [ˈə͡ʊk ˈapə͡l] (IPA) 
Oak apple is a small, round fruit often found on oak trees. Synonyms for this term include oak gall, oak nut, oak cone, and oak marble. These terms are often used interchangeably to describe the same fruit, which is caused by a wasp laying its eggs inside the oak tree leaves. As the eggs hatch, they cause a reaction in the tree that forms the distinctive fruit. While the term oak apple is most commonly used in English-speaking countries, other languages have their own unique words for this fruit, such as "galha-de-carvalho" in Portuguese and "tannapfel" in German.
