An Etymological Dictionary of the German Language/Annotated/Frau
Frau, feminine, ‘mistress, lady, wife, woman,’ from Middle High German vrouwe, Old High German frouwa, feminine, ‘mistress, gentlewoman, lady, wife, woman’; originally perhaps only a High German feminine form (‘wife of the master, mistress of the house’), of Old High German frô, ‘master,’ which became obsolete in German, just as in Romance dominus disappeared in many dialects while domina (in the forms donna, dame) was retained in the entire group; compare Schwieger. See Frohndienst. Frouwa, in the form of frua, found its way into Old Low German, and thence as frú into Scandinavian; the word remained unknown to English. The feminine form was Old Teutonic (Gothic *fraujô, feminine), and was used in Scandinavian — changed according to phonetic laws into Freyja — as the name of a goddess. In the Middle High German period frouwe was popularly connected by a graceful fancy with freuen, fröuwen; compare. Freidank’s saw, “Durch vröude vrouwen sind genant, Ir vröude ervröuwet elliu lant, Wie wol er vröude kante, Der sie êrste vrouwen nante” — “Woman is named from the joy she gives, Her favours fill the world with bliss, What a deep sense of joy had he, Who first named it woman.” See Jungfer and the following word.