1. (Science: botany) a name given to several American trees and shrubs of the same genus (aesculus) as the horse chestnut. The Ohio buckeye, or fetid buckeye, is aesculus glabra. Red buckeye is ae. Pavia. Small buckeye is ae. Paviflora. Sweet buckeye, or yellow buckeye, is ae. Flava.
2. A cant name for a native in Ohio. Buckeye state, Ohio; so called because buckeye trees abound there.