An Etymological Dictionary of the German Language/Annotated/Herr
Herr, masculine, ‘master, lord, gentleman, sir,’ from Middle High German hërre (hêre), masculine, Old High German hē̆rro (hêro), masculine; compare Old Saxon hêrro, Dutch heer, Old Frisian hêra, ‘lord’; properly a comparative of hehr (Old High German hêr), in Gothic *hairiza. In the Old High German period this origin was still recognised, as is seen by Old High German hêrero, ‘lord’ (see herrschen). Since the originally meaning of the adjective hehr was ‘venerable,’ Herr seems to have originated in the relation of the dependants to their master (compare Anglo-Saxon hlaford, ‘bread guardian,’ under Laib), and was used chiefly as a term of address (see Jünger). Compare in Romance the words used in the same sense from Latin senior, viz., Italian signore, French seigneur. Herr is originally native to Germany, but in the form hearra it found is way at a very early period (about the 9th century) from the German lowlands to England, and later to Scandinavia (Modern Swedish herre, ‘master’). In Modern High German only a feminine Herrin has been formed from Herr (as in Italian signora from signore). The older language used Frau, Herr having supplanted the earlier frô (see under frohn).