Horse-chestnut \Horse`-chest"nut\, n. (Bot.)
(a) The large nutlike seed of a species of {[AE]sculus}
({[AE]. Hippocastanum}), formerly ground, and fed to
horses, whence the name.
(b) The tree itself, which was brought from Constantinople
in the beginning of the sixteenth century, and is now
common in the temperate zones of both hemispheres. The
native American species are called {buckeyes}.