horse chestnut

American  

noun

1. a tree, Aesculus hippocastanum, native to the Old World, having digitate leaves and upright clusters of white flowers.

2. the shiny, brown, nutlike seed of this tree or of other trees of the genus Aesculus.

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horse chestnut British  

noun

1. any of several trees of the genus Aesculus, esp the Eurasian A. hippocastanum, having palmate leaves, erect clusters of white, pink, or red flowers, and brown shiny inedible nuts enclosed in a spiky bur: family Hippocastanaceae

2. Also called: conker.  the nut of this tree

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Etymology

Origin of horse chestnut

1590–1600; translation of New Latin castanea equīna; so named from its use in treating respiratory diseases of horses

Example Sentences

Three giant horse chestnut trees, each over 80 feet tall, stand guard in front of my house.

From The Wall Street Journal • Feb. 4, 2026

The single combat involves swinging a conker -- a hardened horse chestnut -- on a string at your opponent's nut with murderous venom, until one is smashed to pieces.

From Barron's • Oct. 17, 2025

A mature horse chestnut, it is festooned with glorious blooms every spring, and after a few weeks sheds hundreds of partially grown, supernumerary conkers, encased in spiky green coverings.

From Seattle Times • May 24, 2024

Each horse chestnut is then graded, precision drilled and laced by volunteers from Ashton Conker Club for the competitors.

From BBC • Oct. 7, 2023

Right at the last second she went like a blur up the side of a horse chestnut tree, stopping just out of reach.

From "Redwall" by Brian Jacques