Dictionary.com Word FAQs
Why do oak trees make acorns? Why aren't they called acorn trees?
The fruit - or mast - of an oak, beech, etc. tree is called an acorn and it originally meant 'fruit of the field or land' in Old English. Various forms were akern, akkorn, accorn, and acorn. In the 15th and 16th century, there arose a tendency to find in the name some connection with "oak" and the forms were popularly taken to be a compound of the ake 'oak tree' and corn 'kernel', hence the modern spelling "acorn." "Oak" itself came into English before 1200 as oc from the Germanic languages. This forest tree was noted for its timber and for bearing a fruit or species of mast, which when it falls on the ground is used for animal food, especially for pigs.