"married woman," 1813, from German Frau "woman, wife," from Middle High German vrouwe "lady, mistress," from Old High German frouwa "mistress, lady" (9c.), from Proto-Germanic *frowo- "lady," fem. of *frawan "lord," from PIE root *per- (1) "beyond, forward," in extended senses "chief, first" (see per).
One's wife: and escort your incomparable frau to a tea dance/ his reward from the frau
[1902+; fr German]