And you, child, will be called a prophet of the Most High, For you will go before the face of the Lord to make ready his ways,

 Mary was betrothed to Joseph. Betrothal lasted for a year and was quite as binding as marriage. It could be dissolved only by divorce. Should the man to whom a girl was betrothed die, in the eyes of the law she was a widow. In the law there occurs the strange-sounding phrase, "a virgin who is a widow." 