The Collaborative International Dictionary of English v.0.48:

Frau \Frau\ (frou), n.; pl. Frauen (frou"en). [G. Cf. 1st
   Frow.]
   In Germany, a woman; a married woman; a wife; -- as a title,
   equivalent to Mrs., Madam.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

Frau
    n 1: a German courtesy title or form of address for an adult
         woman

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "Frau":
   Eve, Fraulein, Miss, Mistress, Mlle, Mme, Mmes, dame,
   daughter of Eve, distaff, domina, dona, donna, dowager, femme,
   frow, gentlewoman, girl, lady, lass, madam, madame, mademoiselle,
   matron, mem-sahib, mesdames, milady, senhora, senhorita, signora,
   signorina, squaw, vrouw, wahine, weaker vessel, woman