The two standard dictionaries of MHG: Mittelhochdeutsches Wörterbuch by Benecke, Müller, and Zarncke (BMZ); and Das Mittelhochdeutsche Handwörterbuch by Lexer (Lexer).
Originally publ. 1807-1811. Includes Wörterbuch zur Erklärung und Verdeutschung der unserer Sprache aufgedrungenen fremden Ausdrücke. Represents the most important collection of the German vocabulary of the classical and romantic periods.
Portal to eleven online German dictionaries published by Uni Trier. Allows cross-searching of all dictionaries at once. Includes Deutsches Wörterbuch (Grimm), Goethe Wörterbuch, MHG dictionaries, and several Mundart dictionaries.