acorn

American  

[ey-kawrn, ey-kern] / ˈeɪ kɔrn, ˈeɪ kərn /

noun

1. the typically ovoid fruit or nut of an oak, enclosed at the base by a cupule.

2. a finial or knop, as on a piece of furniture, in the form of an acorn.

---

acorn British  

/ ˈeɪkɔːn /

noun

1. the fruit of an oak tree, consisting of a smooth thick-walled nut in a woody scaly cuplike base

---

Other Word Forms

• acorned adjective

Etymology

Origin of acorn

before 1000; Middle English acorne (influenced by corn ¹ ), replacing akern, Old English æcern, æcren mast, oak-mast; cognate with Old Norse akarn fruit of wild trees, Middle High German ackeran acorn, Gothic akran fruit, yield < Germanic *akrana-; alleged derivation from base of acre is dubious if original reference was to wild trees

Explanation

The nut, or fruit, that grows on oak trees is called an acorn. Chicken Little thought the sky was falling when an acorn fell on his head. Don't make that same mistake. Acorns are a distinctive nut that's often found on forest floors where oak trees grow. They are smooth and greenish, set in a rough brown base that's shaped like a little cup. The acorn is a seed, able to sprout roots if it falls in the right place, eventually growing into a new oak tree. Many animals eat acorns, some stockpiling the nuts for weeks. In Old English, æcern means "nut," from a Germanic origin.

Example Sentences

They put hot rocks into their tightly woven baskets, along with food like acorn mush, to bring the contents to boil.

From Los Angeles Times • Jan. 8, 2026

According to scientists, the crisis is being driven by a fast-growing bear population, combined with a falling human population and poor acorn harvest pushing bears to seek food elsewhere.

From Barron's • Dec. 24, 2025

Speaking of sides and accompaniments, you need some color: A sheet pan overflowing with a mix of vegetables like acorn squash, sweet potatoes, broccoli/broccolini, Brussel sprouts or anything else that looks good is always beautiful.

From Salon • Oct. 24, 2024

In a peaceful courtyard, a tiny elderly woman stands swirling a batch of home-made acorn jelly, her back hunched from decades of farming.

From BBC • Mar. 12, 2024

To Penelope’s way of thinking, halfway between bark and russet was nowhere near as brown as halfway between acorn and mud.

From "The Interrupted Tale" by Maryrose Wood