noun
1.
a large tall tree with spreading branches, white or pink flowers and nuts that grow inside cases which are covered with spikes
—see also chestnut
2.
the smooth brown nut of the horse chestnut tree
—compare conker
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WORD ORIGIN
late 16th cent.: translating (now obsolete) botanical Latin Castanea equina ; its fruit is said to have been an Eastern remedy for chest diseases in horses.