■ noun
1》 a deciduous tree with large leaves of five leaflets, upright conical clusters of white, pink, or red flowers, and nuts (conkers) enclosed in a spiny case. [ Aesculus hippocastanum and related species.]
2》 a conker.
Origin
C16: translating (now obs.) botanical L. Castanea equina ; its fruit is said to have been an Eastern remedy for chest diseases in horses.