An Etymological Dictionary of the German Language/frank

by Friedrich Kluge

frank, adj., ‘free, independent,’ first occurs in ModHG., from Fr. franc (Ital., Span., and Port. franco), which was again derived from the Teut. tribal name Franken, OHG. Franchun, and may have been applied generally to any freeman. The term Franken is prop. a derivative of a lost OHG. *francho, ‘javelin,’ preserved in AS. franca and OIc. frakke; the Saxons (Sachsen) are similarly named after a weapon — OHG. Sahsun, from sahs, ‘sword’ (see Messer).