fallen woman
if you mean prostitute, use prostitute—or better yet, prostituted woman. Otherwise use for either sex someone who is unfortunate/unlucky/sexually active/promiscuous, someone who has fallen on hard times/from grace. There are no "fallen men" just as there are no "fall women" (see fall guy/fall man); judgments about sexual activity are reserved for women, while judgments about moral evil and foolishness are reserved for men.
