any of various trees or shrubs of the genus Aesculus, as A. glabra(Ohio buckeye) having palmate leaves, gray, scaly bark, and bell-shaped greenish-yellow flowers in upright clusters: the state tree of Ohio.
the brown nut of any of these trees.
(initial capital letter) a native or inhabitant of Ohio (used as a nickname).
a butterfly, Precis lavinia, having dark-brown wings with purple or red eyespots.
Origin: 1755–65, Americanism; buck1 stag + eye, orig. used to designate def. 1, in allusion to the look of the seed
See also horse chestnut any of several North American trees of the genus Aesculus, esp A. glabra (Ohio buckeye), having erect clusters of white or red flowers and prickly fruits: family Hippocastanaceae