oak tree

noun

1. A large, long-living tree with hard wood, deeply lobed leaves and acorns as its fruit; it is one of the most common and best-known trees in Europe and North America.

   A2

   countable

   • "There is a big oak tree in our garden."A2
   • "We sat in the shade of an old oak tree."A2
   • "The oak tree dropped its acorns in autumn."B1
   • "Whole ecosystems depend on the oak tree, which supports hundreds of species of insects and birds."B2

2. Used figuratively to mean something strong, steady and long-lasting, especially in the phrase 'a mighty oak'.

   C1

   literary

   • "Great companies do not appear overnight; a mighty oak grows from a small acorn."C1