Nut

A nut is a simple dry fruit with one seed in which the shell of the fruit becomes very hard at maturity.  Not all nuts are edible.  Some nuts from species birch, alder, hornbeam, wingnut are too small to be worth eating while others like the tanoak species are too bitter to be eaten.  Only a few varieties of nuts can be eaten and be enjoyed.  They include almond, cashew, macadamia, peanuts and many more.

The term nut is also used for seeds, however they are not the same thing.  A seed comes from a fruit that can be removed from the fruit.  However a nut is both the seed and the fruit, which cannot be separated.  Thus the term seeds and nuts cannot be used together.