acorn

Word History: A thoughtful glance at the word acorn might produce the surmise that it is made up of oak and corn, especially if we think of corn in its sense of "a kernel or seed of a plant," as in peppercorn. The fact that others thought the word was so constituted partly accounts for the present form acorn. Here we see the workings of the process of linguistic change known as folk etymology, an alteration in form of a word or phrase so that it resembles a more familiar term mistakenly regarded as analogous. Acorn actually goes back to Old English æcern, "acorn," which in turn goes back to the Indo-European root *ōg-, meaning "fruit, berry."