Original: United Statian is awkward in English, but it exists in Spanish (estadounidense), French (étatsunien(ne), although americain(e) is preferred), Portuguese (estado-unidense or estadunidense), Italian (statunitense), and also in Interlingua (statounitese).
Simplified: United Statian is not used in English, but it exists in Spanish (estadounidense), French (étatsunien(ne)), Portuguese (estado-unidense or estadunidense), Italian (statunitense), and also in Interlingua (statounitese).