# acorn

/ˈeɪkɔɹn/ (US) · /ˈeɪkɔːn/ (UK) · CEFR B2 · Noun

Source: https://englishreference.com/word/acorn
Updated: 2026-05-09

## Definition

the small, brown nut that grows on an oak tree. It has a smooth shell and a little cap on top.

For teachers: the fruit of the oak tree, consisting of a single-seeded nut encased in a cupule. Often used in ecological contexts to discuss forest regeneration or food sources for wildlife.

## Examples

- The squirrel carried an acorn back to its nest.
- During the autumn months, the forest floor is covered in fallen acorns that provide food for deer and birds.
- Ecologists monitor the annual production of acorns to predict fluctuations in the local rodent population, as these nuts are a primary caloric resource during the winter.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.