The oak tree is not a tree of oak but of acorn, otherwise than the chestnut tree. Thus what oak means at all matters after all.
Tree Fruit

See also

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Footnotes
  1. Cf. Korean chamnamu below.
  2. From : tamm "oak" +‎ tõru "acorn". Compare: Korean cham "oak" + dotori "acorn"
  3. lit. "round chestnut". cf. Korean 도토밤 (dotobam) lit. "thick chestnut"