acorn

noun

ˈā-ˌkȯrn  -kərn 

: the nut of the oak usually seated in or surrounded by a hard woody cupule of indurated bracts

Illustration of acorn

Examples of acorn in a Sentence

Recent Examples on the Web

The Millennium Prize Problems are acorn problems, and Navier-Stokes was one of them. — Rivka Galchen, New Yorker, 1 Nov. 2026

Rocky arrived at the Museum of Modern Art swinging a small wooden acorn bag from Chanel’s Métiers d’art 2026 collection on its gold chain. — Hannah Jackson, Vogue, 30 Oct. 2026

Alexis Nikole Nelson–aka @blackforager—instructs her almost three million followers on how to eat acorns. — Rachel Levin, Condé Nast Traveler, 28 Oct. 2026

For small lawns or concentrated piles, start with a flexible leaf rake, which can gather leaves and acorns at the same time. — Tricia Goss, Southern Living, 14 Oct. 2026

Word History

Etymology

Middle English akorn, akkorn (partially assimilated to corn "kernel, corn entry 1"), hakerne, accherne, accharne, going back to Old English æcern, going back to Germanic *akrana- (whence also Middle High German ackeran "tree nuts," Old Norse akarn, Gothic akran "fruit, produce"); akin to Old Irish írne "sloe, kernel," Welsh eirin "plums, sloes," aeron "fruits, berries," going back to Celtic *agrinyo-, *agranyo-; perhaps further akin to a Balto-Slavic word with an initial long vowel (Old Church Slavic agoda "fruit," Polish jagoda "berry," Lithuanian úoga)

Note: Taken to be a derivative of Indo-European *h₂eǵros "uncultivated field, pasture" (see acre), though this would seem to exclude the Balto-Slavic etymon, which lacks the suffix, from consideration. It is also not clear if fields, uncultivated or not, are the source of wild tree nuts.

First Known Use

before the 12th century, in the meaning defined above

Phrases Containing acorn

• acorn squash
• acorn woodpecker
• acorn worm

Kids Definition

acorn

noun

ˈā-ˌkȯrn  -kərn 

: the roundish one-seeded thin-shelled nut of an oak tree usually having a woody cap