The term ACORNS is composed of two words: MAST and NUTS. MAST is a noun that refers to the stem or trunk of a tree, while NUTS are edible seeds or fruits with a hard shell. Acorns are the fruit of the oak tree, which are composed of a hard shell and a soft kernel. They are a popular food source for many animals, including squirrels, deer, and birds. Acorns are also used in traditional medicine and as a source of oil.