Dictionaries authoritative for Scrabble in Languages other than English

Catalan
Diccionari de la Llengua Catalana

Diccionari de la Llengua Catalana d'Enciclophdia Catalana SA (eds. after 1995)
German
21st edition (Auflage) of the Duden Rechtschreibung
Spanish
Diccionario de la Real Academia de Espaņa
Swedish
Svenska Akademiens ordlist, 12th ed.
This is based in some way on Svenska Akademiens ordbok