in·ter·state I. \“+\adjective alsoin·ter·statal\“+\ Etymology:inter- + state or statal : relating to the mutual relations of states : existing between or including different states — used especially of the states of the United States and of the states of Australia < interstate commerce > < interstate highway > II. \ˈintə(r)ˌˌ\noun Usage: often capitalized Etymology:interstate, adjective : any of a system of expressways connecting most major United States cities