/buk"uy'/ , n. , pl. buckeyes .
1. 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.
2. the brown nut of any of these trees.
3. ( cap. ) a native or inhabitant of Ohio (used as a nickname).
4. a butterfly, Precis lavinia, having dark-brown wings with purple or red eyespots.
[ 1755-65, Amer.; BUCK 1 stag + EYE, orig. used to designate def. 1, in allusion to the look of the seed ]