Buckeye \Buck"eye`\, n. 1. (Bot.) A name given to several American trees and shrubs of the same genus ({[AE]sculus}) as the horse chestnut. {The Ohio buckeye}, or {Fetid buckeye}, is {[AE]sculus 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. [U.S.] {Buckeye State}, Ohio; -- so called because buckeye trees abound there.