acorn acorn /ˈeɪˌkɔrn/

noun

1. Fruit of the oak tree: a smooth thin-walled nut in a woody cup-shaped base  ( acorn )
   fruit of the oak tree: a smooth thin-walled nut in a woody cup-shaped base
    Squirrels were busy collecting acorns for the winter.
   Squirrels were busy collecting acorns for the winter.