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 wind carries pollen from a male flower to a female flower, and if all goes well, months later, an acorn develops. —Sheryl De Vore, Chicago Tribune, 16 Mar. 2026

The jewelry was shaped like oak leaves and featured a pavé diamond acorn in the center, inspired by the Middleton family coat of arms. —Christina Perrier, InStyle, 12 Mar. 2026

The choice feels especially fitting for a child who, when the project began in 2020, was a three-year-old whose pockets were perpetually filled with acorns, pinecones, rocks, and sticks. —Kathryn Romeyn, Architectural Digest, 11 Mar. 2026

An oak tree sapling planted recently on a hillside next to the bike path was produced from an acorn from another oak tree about 100 yards away on the same path. —Ashley MacKin Solomon, San Diego Union-Tribune, 3 Mar. 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