Frau (frou) n.
pl.Frau·en (frou'ən) Abbr. Fr. Used as a courtesy title in a German-speaking area before the surname or professional title of an adult woman.
[German, from Middle High German vrowe, from Old High German frouwa; see per1 in Indo-European roots.]
"married woman," c.1813, from Ger. Frau "woman, wife," from M.H.G. vrouwe "lady, mistress," from O.H.G. frouwa "mistress," said to be from PIE *prowo-, from base *per- "beyond."