An Etymological Dictionary of the German Language/Annotated/welsch
welsch, adjective, ‘foreign, outlandish (especially. Italian or French),’ from Middle High German węlsch (węlhisch, walhisch), ‘Romance, French, Italian,’ Old High German walhisc, ‘Romance’; a derivative of Middle High German Walch, Old High German Walh, ‘one of the Latin race.’ The corresponding Anglo-Saxon Wealh was applied to the ‘Kelt,’ and this is the literal meaning of the word (compare the Keltic tribal name Volcae, on which Teutonic Walho- is based; it was applied to the Latin race when they occupied Gaul, which had been formerly inherited by the Kelts. Compare further Walnuß and the English local names Wales (Anglo-Saxon Wălas) and Cornwall.