An orange, along with all citrus fruit, is a hesperidium, which is a "modified berry" with a tough, leathery rind. A berryis any simple fruit produced from a single ovary. Keep in mind, though, that this is the botanical term, and not common parlance. In botany, many items we call "berry," such as a cranberry, strawberry, blackberry, and raspberry, are not actually berries, and many things, such as tomatoes and grapes, are. Knowing what is a berry and what isn't is not really important though, unless you're about to take a botany exam or compete on Jeopardy.