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

Scientists speculated that the uptick in attacks has been driven by a growing bear population, coupled with the year's bad acorn harvest, USA TODAY previously reported. —Mary Walrath-Holdridge, USA Today, 13 May 2026

There Will Be Lots of Acorns A single oak can produce up to 3 million acorns during its lifetime. —Luke Miller, Better Homes & Gardens, 11 May 2026

Bears are thriving thanks in part to an abundance of food — including acorns, deer and boars — under the influence of a warming climate, experts say. —CBS News, 8 May 2026

Despite being an oak in a much smaller package, its foliage and acorns still support lots of wildlife. —Miri Talabac, Baltimore Sun, 28 Apr. 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